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/GrReducedClip.cpp b/src/gpu/GrReducedClip.cpp
index 83079d3..85a19ed 100644
--- a/src/gpu/GrReducedClip.cpp
+++ b/src/gpu/GrReducedClip.cpp
@@ -746,7 +746,7 @@
     // The scratch texture that we are drawing into can be substantially larger than the mask. Only
     // clear the part that we care about.
     GrColor initialCoverage = InitialState::kAllIn == this->initialState() ? -1 : 0;
-    rtc->priv().clear(clip, initialCoverage, true);
+    rtc->priv().clear(clip, initialCoverage, GrRenderTargetContext::CanClearFullscreen::kYes);
 
     // Set the matrix so that rendered clip elements are transformed to mask space from clip space.
     SkMatrix translate;