Enable the OpenGL View renderer on the emulator

If the emulator is run without GL acceleration enabled, the OpenGL
renderer will disable itself at runtime.

Change-Id: Ie40c7895120f51bb6a817c2f3cf7fab0a3dda292

target/board/generic/BoardConfig.mk

@@ -39,3 +39,7 @@ endif
 
 # Build OpenGLES emulation guest and host libraries
 BUILD_EMULATOR_OPENGL := true
+
+# Build and enable the OpenGL ES View renderer. When running on the emulator,
+# the GLES renderer disables itself if host GL acceleration isn't available.
+USE_OPENGL_RENDERER := true