Update go-cty to pull in more stdlib funcs.

I needed "split" specifically so I can do something like:

```hcl
variable PLATFORMS {
  default = "linux/amd64"
}

target foo {
  platforms = split(",", "${PLATFORMS}")
  # other stuff
}
```

Where the existing "csvdecode" does not work for this because it parses
the string into a list of objects instead of a list of strings.

I went ahead and just added all the available new functions.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

vendor/github.com/zclconf/go-cty/cty/function/stdlib/number.go

@@ -2,10 +2,12 @@ package stdlib
 
 import (
 	"fmt"
+	"math"
 	"math/big"
 
 	"github.com/zclconf/go-cty/cty"
 	"github.com/zclconf/go-cty/cty/function"
+	"github.com/zclconf/go-cty/cty/gocty"
 )
 
 var AbsoluteFunc = function.New(&function.Spec{
@@ -358,6 +360,188 @@ var IntFunc = function.New(&function.Spec{
 	},
 })
 
+// CeilFunc is a function that returns the closest whole number greater
+// than or equal to the given value.
+var CeilFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "num",
+			Type: cty.Number,
+		},
+	},
+	Type: function.StaticReturnType(cty.Number),
+	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
+		var val float64
+		if err := gocty.FromCtyValue(args[0], &val); err != nil {
+			return cty.UnknownVal(cty.String), err
+		}
+		if math.IsInf(val, 0) {
+			return cty.NumberFloatVal(val), nil
+		}
+		return cty.NumberIntVal(int64(math.Ceil(val))), nil
+	},
+})
+
+// FloorFunc is a function that returns the closest whole number lesser
+// than or equal to the given value.
+var FloorFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "num",
+			Type: cty.Number,
+		},
+	},
+	Type: function.StaticReturnType(cty.Number),
+	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
+		var val float64
+		if err := gocty.FromCtyValue(args[0], &val); err != nil {
+			return cty.UnknownVal(cty.String), err
+		}
+		if math.IsInf(val, 0) {
+			return cty.NumberFloatVal(val), nil
+		}
+		return cty.NumberIntVal(int64(math.Floor(val))), nil
+	},
+})
+
+// LogFunc is a function that returns the logarithm of a given number in a given base.
+var LogFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "num",
+			Type: cty.Number,
+		},
+		{
+			Name: "base",
+			Type: cty.Number,
+		},
+	},
+	Type: function.StaticReturnType(cty.Number),
+	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
+		var num float64
+		if err := gocty.FromCtyValue(args[0], &num); err != nil {
+			return cty.UnknownVal(cty.String), err
+		}
+
+		var base float64
+		if err := gocty.FromCtyValue(args[1], &base); err != nil {
+			return cty.UnknownVal(cty.String), err
+		}
+
+		return cty.NumberFloatVal(math.Log(num) / math.Log(base)), nil
+	},
+})
+
+// PowFunc is a function that returns the logarithm of a given number in a given base.
+var PowFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "num",
+			Type: cty.Number,
+		},
+		{
+			Name: "power",
+			Type: cty.Number,
+		},
+	},
+	Type: function.StaticReturnType(cty.Number),
+	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
+		var num float64
+		if err := gocty.FromCtyValue(args[0], &num); err != nil {
+			return cty.UnknownVal(cty.String), err
+		}
+
+		var power float64
+		if err := gocty.FromCtyValue(args[1], &power); err != nil {
+			return cty.UnknownVal(cty.String), err
+		}
+
+		return cty.NumberFloatVal(math.Pow(num, power)), nil
+	},
+})
+
+// SignumFunc is a function that determines the sign of a number, returning a
+// number between -1 and 1 to represent the sign..
+var SignumFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "num",
+			Type: cty.Number,
+		},
+	},
+	Type: function.StaticReturnType(cty.Number),
+	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
+		var num int
+		if err := gocty.FromCtyValue(args[0], &num); err != nil {
+			return cty.UnknownVal(cty.String), err
+		}
+		switch {
+		case num < 0:
+			return cty.NumberIntVal(-1), nil
+		case num > 0:
+			return cty.NumberIntVal(+1), nil
+		default:
+			return cty.NumberIntVal(0), nil
+		}
+	},
+})
+
+// ParseIntFunc is a function that parses a string argument and returns an integer of the specified base.
+var ParseIntFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "number",
+			Type: cty.DynamicPseudoType,
+		},
+		{
+			Name: "base",
+			Type: cty.Number,
+		},
+	},
+
+	Type: func(args []cty.Value) (cty.Type, error) {
+		if !args[0].Type().Equals(cty.String) {
+			return cty.Number, function.NewArgErrorf(0, "first argument must be a string, not %s", args[0].Type().FriendlyName())
+		}
+		return cty.Number, nil
+	},
+
+	Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
+		var numstr string
+		var base int
+		var err error
+
+		if err = gocty.FromCtyValue(args[0], &numstr); err != nil {
+			return cty.UnknownVal(cty.String), function.NewArgError(0, err)
+		}
+
+		if err = gocty.FromCtyValue(args[1], &base); err != nil {
+			return cty.UnknownVal(cty.Number), function.NewArgError(1, err)
+		}
+
+		if base < 2 || base > 62 {
+			return cty.UnknownVal(cty.Number), function.NewArgErrorf(
+				1,
+				"base must be a whole number between 2 and 62 inclusive",
+			)
+		}
+
+		num, ok := (&big.Int{}).SetString(numstr, base)
+		if !ok {
+			return cty.UnknownVal(cty.Number), function.NewArgErrorf(
+				0,
+				"cannot parse %q as a base %d integer",
+				numstr,
+				base,
+			)
+		}
+
+		parsedNum := cty.NumberVal((&big.Float{}).SetInt(num))
+
+		return parsedNum, nil
+	},
+})
+
 // Absolute returns the magnitude of the given number, without its sign.
 // That is, it turns negative values into positive values.
 func Absolute(num cty.Value) (cty.Value, error) {
@@ -436,3 +620,34 @@ func Int(num cty.Value) (cty.Value, error) {
 	}
 	return IntFunc.Call([]cty.Value{num})
 }
+
+// Ceil returns the closest whole number greater than or equal to the given value.
+func Ceil(num cty.Value) (cty.Value, error) {
+	return CeilFunc.Call([]cty.Value{num})
+}
+
+// Floor returns the closest whole number lesser than or equal to the given value.
+func Floor(num cty.Value) (cty.Value, error) {
+	return FloorFunc.Call([]cty.Value{num})
+}
+
+// Log returns returns the logarithm of a given number in a given base.
+func Log(num, base cty.Value) (cty.Value, error) {
+	return LogFunc.Call([]cty.Value{num, base})
+}
+
+// Pow returns the logarithm of a given number in a given base.
+func Pow(num, power cty.Value) (cty.Value, error) {
+	return PowFunc.Call([]cty.Value{num, power})
+}
+
+// Signum determines the sign of a number, returning a number between -1 and
+// 1 to represent the sign.
+func Signum(num cty.Value) (cty.Value, error) {
+	return SignumFunc.Call([]cty.Value{num})
+}
+
+// ParseInt parses a string argument and returns an integer of the specified base.
+func ParseInt(num cty.Value, base cty.Value) (cty.Value, error) {
+	return ParseIntFunc.Call([]cty.Value{num, base})
+}