Update ProxyTest to skip configs that don't support the requested sample counts

Bug: skia:
Change-Id: I806dc153b8b6cf6dd6b74549905990cadb55daab
Reviewed-on: https://skia-review.googlesource.com/13871
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
1 file changed