Bug 1204134 - Disallow warnings in config/moz.build. r=glandium.

It was necessary to allow warnings here I introduced ALLOW_COMPILER_WARNINGS in
bug 1198334, but something must have changed subsequently because it no longer
is necessary.

--HG--
extra : rebase_source : 292bd070928b2a0f8f943b8f5dabf31db30244b4

config/moz.build

@@ -43,9 +43,6 @@ PYTHON_UNIT_TESTS += [
 if CONFIG['GNU_CC'] and CONFIG['MOZ_OPTIMIZE']:
     CFLAGS += ['-O3']
 
-# XXX: We should fix these warnings.
-ALLOW_COMPILER_WARNINGS = True
-
 HOST_DEFINES = {
     'UNICODE': True,
     '_UNICODE': True,