Cleanup: More override fixes - include version.

BUG=skia:3075
TEST=ninja -C out/Debug
TBR=reed@google.com

Review URL: https://codereview.chromium.org/800663003
Allow the alpha folding optimization if the single draw's paint has a shader

Let's land this and then leave for 2 weeks.

BUG=skia:3119

Review URL: https://codereview.chromium.org/817033002
remove dead SK_SUPPORT_LEGACY_DEVICE_CLEAR code

BUG=skia:
TBR=robertphilips@google.com

Review URL: https://codereview.chromium.org/807083003
undef SK_SUPPORT_LEGACY_GRADIENT_FACTORIES to fix callers

BUG=skia:
TBR=

Review URL: https://codereview.chromium.org/824533002
removed dead SK_SUPPORT_LEGACY_DRAWTEXT_VIRTUAL code

BUG=skia:
TBR=

Review URL: https://codereview.chromium.org/817193002