Add sys/types.h in utf8.h

Bug: http://b/91353691

It's needed for mode_t.

Test: Build and test Windows modules under Wine.
Change-Id: I3fa6b2946316a9bd2a0d800ae928ba5de480a283

base/include/android-base/utf8.h

@@ -17,6 +17,7 @@
 #pragma once
 
 #ifdef _WIN32
+#include <sys/types.h>
 #include <string>
 #else
 // Bring in prototypes for standard APIs so that we can import them into the utf8 namespace.