build: patch packages supports cgo

compiler/internal/build/build.go

@@ -587,6 +587,13 @@ func buildPkg(ctx *context, aPkg *aPackage, verbose bool) (cgoLdflags []string,
 	check(err)
 	aPkg.LPkg = ret
 	cgoLdflags, err = buildCgo(ctx, aPkg, aPkg.Package.Syntax, externs, verbose)
+	if aPkg.AltPkg != nil {
+		altLdflags, e := buildCgo(ctx, aPkg, aPkg.AltPkg.Syntax, externs, verbose)
+		if e != nil {
+			return nil, e
+		}
+		cgoLdflags = append(cgoLdflags, altLdflags...)
+	}
 	if ctx.output {
 		pkg.ExportFile += ".ll"
 		os.WriteFile(pkg.ExportFile, []byte(ret.String()), 0644)

runtime/internal/lib/runtime/runtime.go

@@ -16,11 +16,13 @@
 
 package runtime
 
-// llgo:skipall
 import (
 	_ "unsafe"
 )
 
+// llgo:skipall
+type _runtime struct{}
+
 // GOROOT returns the root of the Go tree. It uses the
 // GOROOT environment variable, if set at process start,
 // or else the root used during the Go build.