Enable -Wsentinel on linux32, take 2.

I checked that gcc also expands NULL to just 0 here, so
this no longer seems like a clang bug.

BUG=162818

Review URL: https://codereview.chromium.org/437373002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287479 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -2493,11 +2493,6 @@
           '<(DEPTH)/base/allocator/allocator.gyp:type_profiler',
         ],
       }],
-      ['OS=="linux" and clang==1 and host_arch=="ia32"', {
-        # TODO(dmikurube): Remove -Wno-sentinel when Clang/LLVM is fixed.
-        # See http://crbug.com/162818.
-        'cflags+': ['-Wno-sentinel'],
-      }],
       ['branding=="Chrome"', {
         'defines': ['GOOGLE_CHROME_BUILD'],
       }, {  # else: branding!="Chrome"

chrome/browser/ui/libgtk2ui/gtk2_ui.cc

@@ -64,6 +64,13 @@
 // - Render and inject the omnibox background.
 // - Make sure to test with a light on dark theme, too.
 
+// Work around a header bug:
+// linux/debian_wheezy_i386-sysroot/usr/include/linux/stddef.h redefines NULL
+// to 0, which breaks -Wsentinel. Get back the normal definition of NULL.
+// TODO(thakis): Remove this once we update sysroots.
+#define __need_NULL
+#include <stddef.h>
+
 namespace libgtk2ui {
 
 namespace {