[clang-format] Handle spaces in filename paths in clang-format-diff.py (llvm#135779)

This PR resolves an issue in clang-format-diff.py where
filenames containing spaces were not correctly extracted from Git diffs.
Due to the previous regex implementation, filenames were being
truncated, causing the script to fail when processing diffs with such
filenames.

Fixes llvm#135619.

Author: selimkeles

clang/tools/clang-format/clang-format-diff.py

@@ -102,7 +102,7 @@ def main():
     filename = None
     lines_by_file = {}
     for line in sys.stdin:
-        match = re.search(r"^\+\+\+\ (.*?/){%s}(\S*)" % args.p, line)
+        match = re.search(r"^\+\+\+\ (.*?/){%s}(.+)" % args.p, line.rstrip())
         if match:
             filename = match.group(2)
         if filename is None: