Align flags with make

This pulls a number of cflag changes from make since our last sync.

Change-Id: I8c77fc215ed7677b8ac15a6d39143b519068dd55
diff --git a/cc/x86_darwin_host.go b/cc/x86_darwin_host.go
index e497e5c..1bd3dd0 100644
--- a/cc/x86_darwin_host.go
+++ b/cc/x86_darwin_host.go
@@ -65,6 +65,7 @@
 
 	darwinClangCflags = append([]string{
 		"-integrated-as",
+		"-fstack-protector-strong",
 	}, clangFilterUnknownCflags(darwinCflags)...)
 
 	darwinClangLdflags = clangFilterUnknownCflags(darwinLdflags)