Update the contents of libazure

The contents of libazure now reflect 734:46e20d96e909 from
http://hg.mozilla.org/users/bschouten_mozilla.com/moz2d.
Changes to support new libazure

Several things have changed with this incarnation of libazure:
  - Enums have been updated and we must rework some code to deal
    with libazure using strongly-typed enums.
  - CreateDrawTargetSkiaWithGrContextAndFBO was removed, so it has
    been re-added.
  - gfx::ScaledFontSkia can now be created directly from TrueType
    data whereas before it needed a FontInfo.
Merge pull request #117 from mrobinson/libazure-734

Update rust-azure to use Azure commit number 734