Move the default definition of GR_USE_NEW_SHADER_SOURCE_SIGNATURE to GrGLConfig.

R=senorblanco@google.com
Review URL: https://codereview.chromium.org/12390021

git-svn-id: http://skia.googlecode.com/svn/trunk/include@7904 2bbb7eff-a529-9590-31e7-b0007b416f81
4 files changed