Build third-party code with -Wall, build chromium_code with -Wextra on Linux

third_party/mach_override/mach_override.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.
 
 {
   'targets': [
   ],
   'conditions': [
     ['OS=="mac" or (OS=="ios" and "<(GENERATOR)"=="ninja")', {
       'targets' : [
@@ skipping 29 matching lines @@
             # Rather than patching a file that's not relevant, disable it.
             'libudis86/syn-att.c',
             'libudis86/syn-intel.c',
             'libudis86/syn.c',
           ],
           'variables': {
             'clang_warning_flags_unset': [
               # For UD_ASSERT(!"message");
               '-Wstring-conversion',
             ],
+            'clang_warning_flags': [
+              # syn.c contains a switch with an assert(false) in a default:
+              # block.  In release builds, the function is missing a return.
+              '-Wno-return-type',
+              # Fires once in decode.c.
+              '-Wno-sometimes-uninitialized',
+            ],
           },
         },
         {
           'target_name' : 'mach_override',
           'type': 'static_library',
           'toolsets': ['host', 'target'],
           'dependencies': [
             'libudis86',
           ],
           'sources': [
             'mach_override.c',
             'mach_override.h',
           ],
           'include_dirs': [
             '../..',
           ],
         },
       ],
     }],
   ],
 }