Add a DEF_GPUTEST() macro.

This macro is similar to DEF_TEST() and simplifies the process of
setting up a GPU test.

BUG=skia:1952
TEST=tests
R=mtklein@google.com

Review URL: https://codereview.chromium.org/132293005

git-svn-id: http://skia.googlecode.com/svn/trunk@13033 2bbb7eff-a529-9590-31e7-b0007b416f81
18 files changed