[build] Lift c++11 restriction

Bug: v8:9687
Change-Id: Ia9e82e1565d2dca595f5a231281d415f423b3421
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1787421Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63571}

infra/mb/mb_config.pyl

@@ -648,8 +648,7 @@
     },
 
     'gcc': {
-      # TODO(machenbach): Remove cxx11 restriction when updating gcc version.
-      'gn_args': 'is_clang=false use_cxx11=true',
+      'gn_args': 'is_clang=false',
     },
 
     'gcmole': {