Load the default graphics driver in USAPs.

This patch causes unspecialized app processes to load the OpenGL driver
after they are forked.  The ZygoteProcess code will then take an
application's driver preference into account when selecting how to
launch it.

Test: m & boot & launch & inspect traces for driver loading
Bug: 130029351
Change-Id: If6fa02f9c387596162e75a685b04208b45a5c86b
Merged-In: If6fa02f9c387596162e75a685b04208b45a5c86b
(cherry picked from commit 301a1c46)