Bump the macOS version to 10.10.

Android Studio only claims to support macOS 10.10 and later, so we
probably shouldn't bother with anything older either.

Test: treehugger
Change-Id: I478cb52221198d7b7e2247dfbee4cd86d5bbd1a8
diff --git a/cc/config/x86_darwin_host.go b/cc/config/x86_darwin_host.go
index 000228d..25225b5 100644
--- a/cc/config/x86_darwin_host.go
+++ b/cc/config/x86_darwin_host.go
@@ -100,7 +100,7 @@
 	pctx.VariableFunc("macSdkRoot", func(ctx android.PackageVarContext) string {
 		return xcrunSdk(ctx, "--show-sdk-path")
 	})
-	pctx.StaticVariable("macMinVersion", "10.9")
+	pctx.StaticVariable("macMinVersion", "10.10")
 	pctx.VariableFunc("MacArPath", func(ctx android.PackageVarContext) string {
 		return xcrun(ctx, "--find", "ar")
 	})