checkpatch: handle C99 comments correctly (performance issue)

This fixes the sanitation process in checkpatch.pl so that it blocks out
the text after a C99 style comment the same way it does with block style
comments.  This prevents the text from getting processed as regular code.

Signed-off-by: Daniel Walker <dwalker@fifo99.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>