Avoid zlib symbol conflicts in open-vcdiff

sdch/sdch.gyp

 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 29 matching lines @@
         'open-vcdiff/src/vcdiffengine.cc',
         'open-vcdiff/src/vcdiffengine.h',
         'open-vcdiff/src/zconf.h',
         'open-vcdiff/src/zlib.h',
         'open-vcdiff/vsprojects/config.h',
         'open-vcdiff/vsprojects/stdint.h',
       ],
       'include_dirs': [
         'open-vcdiff/src',
       ],
+      'defines': [
+        # Prefix the local zlib function names (e.g. adler32 -> z_adler32) to
+        # avoid link warning due to name conflict with zlib.
+        'Z_PREFIX',

[tonyg, 2012/03/01 11:32:54]

Sorry for the naive question, but why is there a local zlib in the first place.
If it is unmodified can we remove it? If it is heavily modified, should it just
be renamed so as to not conflict in the first place?

[Xianzhu, 2012/03/01 17:44:44]

Good question. I just compared sdch/open-vcdiff/src/adler32.c and
third_party/zlib/adler32.c and I believe the differences won't have any effect.
I'll try to let sdch depend on zlib.

+      ],
       'direct_dependent_settings': {
         'include_dirs': [
           'open-vcdiff/src',
         ],
       },
       'conditions': [
         [ 'OS == "linux" or OS == "android"', { 'include_dirs': [ 'linux' ] } ],
         [ 'os_bsd==1 or OS=="solaris"', { 'include_dirs': [ 'bsd' ] } ],
         [ 'OS == "mac"', { 'include_dirs': [ 'mac' ] } ],
         [ 'OS == "win"', { 'include_dirs': [ 'open-vcdiff/vsprojects' ] } ],
       ],
     },
   ],
 }