Reduce the size of libhwui by 50%

This change removes unnessary symbols. All symbols are hidden by
default, public APIs with exported symbols are explicitly marked
with ANDROID_API.

Change-Id: I692fde432a86c12108de1cfd1f6504919a7d5f3f

include/utils/Singleton.h

@@ -20,12 +20,13 @@
 #include <stdint.h>
 #include <sys/types.h>
 #include <utils/threads.h>
+#include <cutils/compiler.h>
 
 namespace android {
 // ---------------------------------------------------------------------------
 
 template <typename TYPE>
-class Singleton
+class ANDROID_API Singleton
 {
 public:
     static TYPE& getInstance() {