Revert of Move from libstlport to libc++ for Android framework builds (patchset #1 id:1 of https://codereview.chromium.org/714113002/)

Reason for revert:
The code this depends on is not ready yet. We can submit once https://android-review.googlesource.com/#/c/113924/ is submitted.

Original issue's description:
> Move from libstlport to libc++ for Android framework builds
>
> Committed: https://skia.googlesource.com/skia/+/ce259510a738fab05a0d456440104f5aba1c9d72

TBR=tomhudson@google.com,djsollen@google.com
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/718793003
Add GrGpuResource::CacheAccess

Internal only helper class for manipulating and accessing cache keys.

BUG=skia:2889

Review URL: https://codereview.chromium.org/703303003
Add isUnblended query to GrDrawState.

BUG=skia:

Review URL: https://codereview.chromium.org/715873002