Disable acceleration when the context is legacy graphics.

bug 13728313

Change-Id: I63d8a352cc6d44f1b87ba5ded7f95b297f512e92
diff --git a/rsContext.cpp b/rsContext.cpp
index 1bcea6b..916c6a0 100644
--- a/rsContext.cpp
+++ b/rsContext.cpp
@@ -324,7 +324,7 @@
 
     if (getProp("debug.rs.default-CPU-driver") != 0) {
         ALOGD("Skipping override driver and loading default CPU driver");
-    } else if (rsc->mForceCpu) {
+    } else if (rsc->mForceCpu || rsc->mIsGraphicsContext) {
         ALOGV("Application requested CPU execution");
     } else if (rsc->getContextType() == RS_CONTEXT_TYPE_DEBUG) {
         ALOGV("Application requested debug context");