Avoid

  unexpected clang version 16.0.0 (not 16), update RELEASE_VERSION in update.py

error at the end of the clang building process.

--- tools/clang/scripts/build.py.orig	2023-02-13 00:41:59.394397795 +0100
+++ tools/clang/scripts/build.py	2023-02-13 13:47:32.941126748 +0100
@@ -430,7 +430,7 @@
     clang += '-cl.exe'
   version_out = subprocess.check_output([clang, '--version'],
                                         universal_newlines=True)
-  version_out = re.match(r'clang version ([0-9.]+)', version_out).group(1)
+  version_out = re.match(r'clang version ([0-9]+)', version_out).group(1)
   if version_out != RELEASE_VERSION:
     print(('unexpected clang version %s (not %s), '
            'update RELEASE_VERSION in update.py')