allow fiddles to use the futex system call; fixes fonts finally

BUG=skia:

Review URL: https://codereview.chromium.org/639013002
repair the webtry setup process

The previous version of the script didn't properly update the code for the webtry
user, so only changes to skia would really be pulled, not changes to the actual
webtry server itself.

This version of the setup script is 100% automated and brings everything up to date.

It's also a little more verbose about what it's doing, so it's easier to debug.

BUG=skia:
R=tfarina@chromium.org
TBR=jcgregorio, mtklein, tfarina

Review URL: https://codereview.chromium.org/636173003
pre-build the resources library for the fiddle jail

BUG=skia:
TBR=jcgregorio

Review URL: https://codereview.chromium.org/637353003
Rebase Nexus 10 gm failure

TBR=robertphillips@google.com

BUG=skia:

Review URL: https://codereview.chromium.org/638043002
Add SK_API to GrGpuResource
TBR=reed@google.com

Review URL: https://codereview.chromium.org/638963003
Use presence of a content key as non-scratch indicator

BUG=skia:2889

Review URL: https://codereview.chromium.org/639873002