misc/cgo/errors: don't pass -C to compiler

It's not needed, and the current expectation is that it will go away
in the future.

Change-Id: I5f46800e748d9ffa484bda6d1738290c8e00ac2b
Reviewed-on: https://go-review.googlesource.com/63751
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Author: ianlancetaylor

misc/cgo/errors/errors_test.go

@@ -63,7 +63,7 @@ func expect(t *testing.T, file string, errors []*regexp.Regexp) {
 	defer os.RemoveAll(dir)
 
 	dst := filepath.Join(dir, strings.TrimSuffix(file, ".go"))
-	cmd := exec.Command("go", "build", "-o="+dst, "-gcflags=-C", path(file))
+	cmd := exec.Command("go", "build", "-o="+dst, path(file))
 	out, err := cmd.CombinedOutput()
 	if err == nil {
 		t.Errorf("expected cgo to fail but it succeeded")