Also update LD_LIBRARY_PATH to include the LIBGL_DRIVERS_PATH.
BUG=skia:
Change-Id: I0b4d3237f8042ac739f184b107f1c85368b71ee2
Reviewed-on: https://skia-review.googlesource.com/8603
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
