Move libutils off AndroidConfig.h.

Change-Id: Ia0e4a4f968c640eb44317821d2dc6b195f9f490e
diff --git a/libutils/String8.cpp b/libutils/String8.cpp
index 3323b82..28be60f 100644
--- a/libutils/String8.cpp
+++ b/libutils/String8.cpp
@@ -16,6 +16,7 @@
 
 #include <utils/String8.h>
 
+#include <utils/Compat.h>
 #include <utils/Log.h>
 #include <utils/Unicode.h>
 #include <utils/SharedBuffer.h>