Prefer fullscreen clears on Qualcomm/GL

Adds Qualcomm to the set of GL devices on which we prefer fullscreen
clears.

Renames fullscreenClearIsFree in GrCaps to preferFullscreenClears.

Replaces 'bool canIgnoreClip' on GrRenderTargetContext::clear with an
enum.

Bug: skia:
Change-Id: I5b30298c4d0b092c398b9fea6060f3e2bea91e46
Reviewed-on: https://skia-review.googlesource.com/83060
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/tests/GrMeshTest.cpp b/tests/GrMeshTest.cpp
index b89e198..07b5999 100644
--- a/tests/GrMeshTest.cpp
+++ b/tests/GrMeshTest.cpp
@@ -389,7 +389,7 @@
     }
 
     SkAutoSTMalloc<kImageHeight * kImageWidth, uint32_t> resultPx(h * rowBytes);
-    rtc->clear(nullptr, 0xbaaaaaad, true);
+    rtc->clear(nullptr, 0xbaaaaaad, GrRenderTargetContext::CanClearFullscreen::kYes);
     rtc->priv().testingOnly_addDrawOp(skstd::make_unique<GrMeshTestOp>(testFn));
     rtc->readPixels(gold.info(), resultPx, rowBytes, 0, 0, 0);
     for (int y = 0; y < h; ++y) {