Fix Clang warnings/errors

Fix several build warnings (struct != class, int != size_t) and errors
(variable leng non-POD arrays).

Change-Id: I70b4e784365514303d8954bfcb1f39d7c22c1321
diff --git a/libs/hwui/Patch.h b/libs/hwui/Patch.h
index 763a785..489064b 100644
--- a/libs/hwui/Patch.h
+++ b/libs/hwui/Patch.h
@@ -36,7 +36,8 @@
 // 9-patch structures
 ///////////////////////////////////////////////////////////////////////////////
 
-struct Patch {
+class Patch {
+public:
     Patch();
     ~Patch();