cairo, pixman: upgraded packages to upstream

Upgraded x11-libs/cairo to version 1.12.12 on amd64, arm, x86
Upgraded x11-libs/pixman to version 0.28.2 on amd64, arm, x86

These had to be done together due to version interdependencies.

In both cases, the respective ebuild files differ from their
upstream versions only as follows:

  () Edited EAPI 5 down to EAPI 4
  () Edited KEYWORDS to mark amd64, arm, x86 as stable

BUG=None
TEST=Build chroot with clean repo and run available media test

CQ-DEPEND=CL:Id7987ae5e8a9bb3bc156a4534f9bef1496e97243

Change-Id: I17e4d3cb8397189444ed0a1a1a0ad0b413f446f3
Reviewed-on: https://gerrit.chromium.org/gerrit/51180
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Sathish Kuppuswamy <sathish.kuppuswamy@intel.com>
Commit-Queue: Josh Triplett <josh@joshtriplett.org>
14 files changed