crypto/tls: quiet build

On a Mac, all the useful functions are deprecated.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5493054

src/pkg/crypto/tls/root_darwin.go

@@ -8,7 +8,7 @@ package tls
 // Note: We disable -Werror here because the code in this file uses a deprecated API to stay
 // compatible with both Mac OS X 10.6 and 10.7. Using a deprecated function on Darwin generates
 // a warning.
-#cgo CFLAGS: -Wno-error
+#cgo CFLAGS: -Wno-error -Wno-deprecated-declarations
 #cgo LDFLAGS: -framework CoreFoundation -framework Security
 #include <CoreFoundation/CoreFoundation.h>
 #include <Security/Security.h>