Add counter for failed pulld installs.
Add counter for failed pulld installs.

BUG=skia:4960

Change-Id: I521f0f3f3c3cf15fcf78563f0b068d69a348b6a6
Reviewed-on: https://skia-review.googlesource.com/9147
Reviewed-by: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>
Commit-Queue: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot