[gcc r12-8251] contrib: filter out a new Clang warning

[Martin Liska]

https://gcc.gnu.org/g:68fd1c9f22ad42536bcb63a4c776004268702b0b

commit r12-8251-g68fd1c9f22ad42536bcb63a4c776004268702b0b
Author: Martin Liska <mliska@suse.cz>
Date:   Mon Apr 25 22:26:27 2022 +0200

    contrib: filter out a new Clang warning
    
    Filter out:
    libcpp/lex.cc:1289:7: warning: use of the 'likely' attribute is a C++20 extension [-Wc++20-attribute-extensions]
    
    contrib/ChangeLog:
    
            * filter-clang-warnings.py: Filter out
            -Wc++20-attribute-extensions in lex.cc.

Diff:
---
 contrib/filter-clang-warnings.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/contrib/filter-clang-warnings.py b/contrib/filter-clang-warnings.py
index 405ab8da6da..942cd30b659 100755
--- a/contrib/filter-clang-warnings.py
+++ b/contrib/filter-clang-warnings.py
@@ -53,7 +53,8 @@ def skip_warning(filename, message):
             'genautomata.cc': ['-Wstring-plus-int'],
             'fold-const-call.cc': ['-Wreturn-type'],
             'gfortran.texi': [''],
-            'libtool': ['']
+            'libtool': [''],
+            'lex.cc': ['-Wc++20-attribute-extensions'],
     }
 
     for name, ignores in ignores.items():