Add support for Go 1.16.

cgo/cgo_test.go

@@ -5,6 +5,7 @@ import (
 	"flag"
 	"fmt"
 	"go/ast"
+	"go/build"
 	"go/format"
 	"go/parser"
 	"go/token"
@@ -41,6 +42,20 @@ func TestCGo(t *testing.T) {
 	for _, name := range []string{"basic", "errors", "types", "flags", "const"} {
 		name := name // avoid a race condition
 		t.Run(name, func(t *testing.T) {
+			// Skip tests that require specific Go version.
+			if name == "errors" {
+				ok := false
+				for _, version := range build.Default.ReleaseTags {
+					if version == "go1.16" {
+						ok = true
+						break
+					}
+				}
+				if !ok {
+					t.Skip("Results for errors test are only valid for Go 1.16+")
+				}
+			}
+
 			// Read the AST in memory.
 			path := filepath.Join("testdata", name+".go")
 			fset := token.NewFileSet()