miniz support in SkFlate / PDF
   - Adds miniz.c v115_r4 (latest release) to third_party.
   - Merges SkDeflateWStream into SkFlate so including "miniz.c" links
     without duplicating symbols.

The only interesting code change I've made is to remove the line
     fImpl->fZStream.data_type = Z_BINARY;
from SkDeflateWStream::SkDeflateWStream().  miniz doesn't have Z_BINARY
defined, and as far as I can tell, both zlib and miniz ignore data_type.

We should be able to swap skflate.gyp's dependency between zlib.gyp:zlib and
zlib.gyp:miniz at will (except of course on Windows) if we're interested in
zlib itself.  I've left android framework on its own zlib.  I think this all
means we can stop defining SK_NO_FLATE on Windows.

I'll leave the possible cleanup of SK_NO_FLATE itself for another time.  Might
be we always want to keep this dependency optional.

CQ_EXTRA_TRYBOTS=client.skia:Test-Win8-ShuttleA-HD7770-x86-Debug-Trybot

BUG=skia:

Review URL: https://codereview.chromium.org/957323003
13 files changed