EGL: Add stubs for EGL_ANDROID_blob_cache

This change adds a stub cache implementation that gets passed to the
underlying EGL implementation at initialization time.

Change-Id: I14437c5b6f91b7a34a19bb02ad802e6e54f88d2a
diff --git a/opengl/libs/EGL/eglApi.cpp b/opengl/libs/EGL/eglApi.cpp
index 1f9ce68..60ac34b 100644
--- a/opengl/libs/EGL/eglApi.cpp
+++ b/opengl/libs/EGL/eglApi.cpp
@@ -858,10 +858,17 @@
         return  NULL;
     }
 
+    // The EGL_ANDROID_blob_cache extension should not be exposed to
+    // applications.  It is used internally by the Android EGL layer.
+    if (!strcmp(procname, "eglSetBlobCacheFuncs")) {
+        return NULL;
+    }
+
     __eglMustCastToProperFunctionPointerType addr;
     addr = findProcAddress(procname, sExtentionMap, NELEM(sExtentionMap));
     if (addr) return addr;
 
+
     // this protects accesses to sGLExtentionMap and sGLExtentionSlot
     pthread_mutex_lock(&sExtensionMapMutex);