It's somewhat common and in general a defect for c90 keywords to
not start on a tabstop.

Add a test for this condition and warn when it occurs.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>