cmd/cgo/internal/testsanitizers: check for go build and cgo in fuzzer…

… and msan tests

Check if the platform can compile programs and has cgo support as a
requirement to run the fuzzer and msan tests.

Fixes [reserved]

src/cmd/cgo/internal/testsanitizers/libfuzzer_test.go

@@ -7,11 +7,14 @@
 package sanitizers_test
 
 import (
+	"internal/testenv"
 	"strings"
 	"testing"
 )
 
 func TestLibFuzzer(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+	testenv.MustHaveCGO(t)
 	goos, err := goEnv("GOOS")
 	if err != nil {
 		t.Fatal(err)

src/cmd/cgo/internal/testsanitizers/msan_test.go

@@ -8,11 +8,14 @@ package sanitizers_test
 
 import (
 	"internal/platform"
+	"internal/testenv"
 	"strings"
 	"testing"
 )
 
 func TestMSAN(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+	testenv.MustHaveCGO(t)
 	goos, err := goEnv("GOOS")
 	if err != nil {
 		t.Fatal(err)