Better fix for GL wallpaper creation

A previous fix made initializing GL work better by calling eglMakeCurrent()
prior to querying the max texture size. However, that fix worked by creating an eglSurface
earlier than we did before, which for some reason causes problems later if wallpaper creation
fails and we back off to a software solution.

This new fix creates a temporary pbuffer surface instead, which still allows us to make the
call to eglMakeCurrent() prior to querying the max texture size, but does not result in the
later canvas lock failure if the wallpaper creation fails anyway.

Issue #8319960 sluggish yakju animations over launcher

Change-Id: I394d672549260a354f03ad9fd1b9e1f9a161a371