This is to fix error messages when running GLES1 samples (and probably
other apps) from different directories than the same one as where
libGLESv1_CM.dylib is located.

BUG=angleproject:2306

Change-Id: I24ab33eb1bc805c1e64efab9a0acbfcf10480d94
Reviewed-on: https://chromium-review.googlesource.com/920926Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Lingfeng Yang <lfy@google.com>