Merge pull request #40 from ebriney/osx10.10-10.11-compatibility

Add cgo flags to support older version of OSX (10.10, 10.11)

Author: vdemeester

osxkeychain/osxkeychain_darwin.go

@@ -1,8 +1,8 @@
 package osxkeychain
 
 /*
-#cgo CFLAGS: -x objective-c
-#cgo LDFLAGS: -framework Security -framework Foundation
+#cgo CFLAGS: -x objective-c -mmacosx-version-min=10.10
+#cgo LDFLAGS: -framework Security -framework Foundation -mmacosx-version-min=10.10
 
 #include "osxkeychain_darwin.h"
 #include <stdlib.h>