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>

tests/ProxyTest.cpp

@@ -213,6 +213,7 @@ DEF_GPUTEST_FOR_RENDERING_CONTEXTS(WrappedProxyTest, reporter, ctxInfo) {
         for (auto config : { kAlpha_8_GrPixelConfig, kRGBA_8888_GrPixelConfig }) {
             for (auto budgeted : { SkBudgeted::kYes, SkBudgeted::kNo }) {
                 for (auto numSamples: { 0, 4}) {
+                    if (caps.maxSampleCount() < numSamples) continue;
                     bool renderable = caps.isConfigRenderable(config, numSamples > 0);
 
                     GrSurfaceDesc desc;