hide lockpixels api behind flag

guarded by SK_SUPPORT_OBSOLETE_LOCKPIXELS

needs https://codereview.chromium.org/2820873002/# to land first
Bug: skia:6481
Change-Id: I1c39902cbf6fe99f622adfa8192733b95f7fea09

Change-Id: I1c39902cbf6fe99f622adfa8192733b95f7fea09
Reviewed-on: https://skia-review.googlesource.com/13580
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Mike Reed <reed@google.com>
86 files changed