vendor: update buildkit to master@8b7bcb900d3c

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/golang.org/x/sys/cpu/hwcap_linux.go

@@ -24,6 +24,21 @@ var hwCap uint
 var hwCap2 uint
 
 func readHWCAP() error {
+	// For Go 1.21+, get auxv from the Go runtime.
+	if a := getAuxv(); len(a) > 0 {
+		for len(a) >= 2 {
+			tag, val := a[0], uint(a[1])
+			a = a[2:]
+			switch tag {
+			case _AT_HWCAP:
+				hwCap = val
+			case _AT_HWCAP2:
+				hwCap2 = val
+			}
+		}
+		return nil
+	}
+
 	buf, err := ioutil.ReadFile(procAuxv)
 	if err != nil {
 		// e.g. on android /proc/self/auxv is not accessible, so silently

vendor/golang.org/x/sys/cpu/runtime_auxv.go

@@ -0,0 +1,16 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cpu
+
+// getAuxvFn is non-nil on Go 1.21+ (via runtime_auxv_go121.go init)
+// on platforms that use auxv.
+var getAuxvFn func() []uintptr
+
+func getAuxv() []uintptr {
+	if getAuxvFn == nil {
+		return nil
+	}
+	return getAuxvFn()
+}

vendor/golang.org/x/sys/cpu/runtime_auxv_go121.go

@@ -0,0 +1,19 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.21
+// +build go1.21
+
+package cpu
+
+import (
+	_ "unsafe" // for linkname
+)
+
+//go:linkname runtime_getAuxv runtime.getAuxv
+func runtime_getAuxv() []uintptr
+
+func init() {
+	getAuxvFn = runtime_getAuxv
+}