Attempt to work around iOS varying limit in GLPrograms test

Dump shaders when linking fails.

Bug: skia:6627
Change-Id: I7f1df4be039eb56d990aa64c58c8dd2a22d97dbe
Reviewed-on: https://skia-review.googlesource.com/16867
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
10 files changed