Issue #1274 - Part 1: Adopt the cairo version as our own.

- Move header licensing from tri-license to MPL 2.0. MPL-compatible
  other licensing has been retained where originally present.
- Remove individual superseded licensing terms.
- Remove patches, outdated readmes & incomplete patch summaries.
- Remove incomplete cairo release notes (only went up to 1.6.4 anyway).
- Rewrite COPYING to indicate the current state of the library in tree.

gfx/cairo/moz.build

@@ -1,11 +0,0 @@
-# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
-# vim: set filetype=python:
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-DIRS += ['cairo/src']
-
-if CONFIG['MOZ_TREE_PIXMAN']:
-    DIRS += ['libpixman/src']
-