don't prefer 16bpp surface formats by default

Change-Id: I52dbe17911c0a56a9c962c89f15da43198e27ff2
Revert "Simplify OpenGL TLS access on ARM."

This reverts commit 288870ebc3da8121b7a237a53280bd8b931b7a2f.

Conflicts:

	opengl/libagl/Android.mk
	opengl/libs/EGL/getProcAddress.cpp
	opengl/libs/GLES2/gl2.cpp
	opengl/libs/GLES_CM/gl.cpp

Change-Id: I1401ab19e3035c1ed132781f126aafc5149d66ae