Bug 1765474 - Disable warnings in modules/zlib. r=firefox-build-system-reviewers,mhentges

Differential Revision: https://phabricator.services.mozilla.com/D144142

modules/zlib/src/moz.build

@@ -34,3 +34,6 @@ SOURCES += [
     'uncompr.c',
     'zutil.c',
 ]
+
+# We allow warnings for third-party code that can be updated from upstream.
+AllowCompilerWarnings()