Add flag to disable 64-bit driver.

bug 17428047

Change-Id: I888dd310449bf9079e352cb4aef31344c05b0ba8
diff --git a/Android.mk b/Android.mk
index e8ec005..b14d2d8 100644
--- a/Android.mk
+++ b/Android.mk
@@ -10,6 +10,10 @@
   rs_base_CFLAGS += -DOVERRIDE_RS_DRIVER=$(OVERRIDE_RS_DRIVER)
 endif
 
+ifneq ($(DISABLE_RS_64_BIT_DRIVER),)
+  rs_base_CFLAGS += -DDISABLE_RS_64_BIT_DRIVER
+endif
+
 ifeq ($(RS_FIND_OFFSETS), true)
   rs_base_CFLAGS += -DRS_FIND_OFFSETS
 endif
diff --git a/rsContext.cpp b/rsContext.cpp
index 2112ace..e1a7c71 100644
--- a/rsContext.cpp
+++ b/rsContext.cpp
@@ -333,12 +333,16 @@
     } else if (rsc->getContextType() == RS_CONTEXT_TYPE_DEBUG) {
         ALOGV("Application requested debug context");
     } else {
+#if defined(__LP64__) && defined(DISABLE_RS_64_BIT_DRIVER)
+        // skip load
+#else
         if (loadRuntime(OVERRIDE_RS_DRIVER_STRING, rsc)) {
             ALOGV("Successfully loaded runtime: %s", OVERRIDE_RS_DRIVER_STRING);
             loadDefault = false;
         } else {
             ALOGE("Failed to load runtime %s, loading default", OVERRIDE_RS_DRIVER_STRING);
         }
+#endif
     }
 
 #undef XSTR