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/src/gpu/ccpr/GrCCPRAtlas.cpp b/src/gpu/ccpr/GrCCPRAtlas.cpp
index 8978e31..497241d 100644
--- a/src/gpu/ccpr/GrCCPRAtlas.cpp
+++ b/src/gpu/ccpr/GrCCPRAtlas.cpp
@@ -116,7 +116,7 @@
     }
 
     SkIRect clearRect = SkIRect::MakeSize(fDrawBounds);
-    rtc->clear(&clearRect, 0, true);
+    rtc->clear(&clearRect, 0, GrRenderTargetContext::CanClearFullscreen::kYes);
     rtc->addDrawOp(GrNoClip(), std::move(atlasOp));
 
     fTextureProxy = sk_ref_sp(rtc->asTextureProxy());