cmd/go: skip slow tests on mips when run under builders

Change-Id: If754de6c44cf0ec4192101432e4065cc7a28e862
Reviewed-on: https://go-review.googlesource.com/33425Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

src/cmd/go/go_test.go

@@ -49,6 +49,17 @@ func init() {
 			// many linux/arm machines are too slow to run
 			// the full set of external tests.
 			skipExternal = true
+		case "mips", "mipsle", "mips64", "mips64le":
+			// Also slow.
+			skipExternal = true
+			if testenv.Builder() != "" {
+				// On the builders, skip the cmd/go
+				// tests. They're too slow and already
+				// covered by other ports. There's
+				// nothing os/arch specific in the
+				// tests.
+				canRun = false
+			}
 		}
 	case "freebsd":
 		switch runtime.GOARCH {