vendor: add buildkit

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/moby/buildkit/solver/pb/platform.go

@@ -0,0 +1,41 @@
+package pb
+
+import (
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+func (p *Platform) Spec() specs.Platform {
+	return specs.Platform{
+		OS:           p.OS,
+		Architecture: p.Architecture,
+		Variant:      p.Variant,
+		OSVersion:    p.OSVersion,
+		OSFeatures:   p.OSFeatures,
+	}
+}
+
+func PlatformFromSpec(p specs.Platform) Platform {
+	return Platform{
+		OS:           p.OS,
+		Architecture: p.Architecture,
+		Variant:      p.Variant,
+		OSVersion:    p.OSVersion,
+		OSFeatures:   p.OSFeatures,
+	}
+}
+
+func ToSpecPlatforms(p []Platform) []specs.Platform {
+	out := make([]specs.Platform, 0, len(p))
+	for _, pp := range p {
+		out = append(out, pp.Spec())
+	}
+	return out
+}
+
+func PlatformsFromSpec(p []specs.Platform) []Platform {
+	out := make([]Platform, 0, len(p))
+	for _, pp := range p {
+		out = append(out, PlatformFromSpec(pp))
+	}
+	return out
+}