workaroud [1964234] emulator renders funny with new gralloc.

we detect we're running on the emu (using a very bad heuristic, see 1964251) and switch UPDATE_ON_DEMAND off.
diff --git a/modules/gralloc/framebuffer.cpp b/modules/gralloc/framebuffer.cpp
index 248a2fc..2d0fa25 100644
--- a/modules/gralloc/framebuffer.cpp
+++ b/modules/gralloc/framebuffer.cpp
@@ -41,6 +41,10 @@
 // should be a build option
 #define SUPPORTS_UPDATE_ON_DEMAND   1
 
+// fb_fix_screeninfo::id returned on the emulator
+#define EMULATOR_DEV_FB_ID ""
+
+// numbers of buffers for page flipping
 #define NUM_BUFFERS 2
 
 
@@ -366,6 +370,12 @@
             const_cast<int&>(dev->device.minSwapInterval) = 1;
             const_cast<int&>(dev->device.maxSwapInterval) = 1;
 
+            if (!strcmp(m->finfo.id, EMULATOR_DEV_FB_ID)) {
+                LOGD("I think we're running on the emulator, "
+                     "turning UPDATE_ON_DEMAND off");
+                dev->device.setUpdateRect = 0;
+            }
+            
             *device = &dev->device.common;
         }
     }