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/SkiaShader.h b/libs/hwui/SkiaShader.h
index 9fc99a4..d71f8ee 100644
--- a/libs/hwui/SkiaShader.h
+++ b/libs/hwui/SkiaShader.h
@@ -43,7 +43,8 @@
  * Represents a Skia shader. A shader will modify the GL context and active
  * program to recreate the original effect.
  */
-struct SkiaShader {
+class SkiaShader {
+public:
     /**
      * Type of Skia shader in use.
      */