Improve RS error handling.  On errors RS will now store the error and a message that can be read from the app.  RS will then not continue rendering frames while an unchecked error is present until new state is received.
diff --git a/rsShaderCache.h b/rsShaderCache.h
index 7aa8183..df99ccc 100644
--- a/rsShaderCache.h
+++ b/rsShaderCache.h
@@ -56,6 +56,7 @@
         int32_t mFragAttribSlots[Program::MAX_ATTRIBS];
         int32_t mFragUniformSlots[Program::MAX_UNIFORMS];
         bool mUserVertexProgram;
+        bool mIsValid;
     } entry_t;
     entry_t *mEntries;
     entry_t *mCurrent;