Fix a violated precondition in clang-format.

Make sure we do not try to change line comments that are non-regular, i.e. do
not start with "//" or "#". This can for example happen when "//" is
broken into two lines with an escaped newline.

GitOrigin-RevId: 4dcfae6a003aa541600e5af42c0bec5d8e1abef0
2 files changed