preproc: style cleanups
preproc: style cleanups

Fix indentation, space between if and (, and prefer (foo) and (!foo)
to (foo != NULL) and (foo == NULL).

Signed-off-by: H. Peter Anvin <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>

projedi/nasm,letolabs/nasm,Distrotech/nasm,Distrotech/nasm,techkey/nasm,turingstudio/nasm,techkey/nasm,Distrotech/nasm,projedi/nasm,letolabs/nasm,Distrotech/nasm,turingstudio/nasm,techkey/nasm,projedi/nasm,projedi/nasm,turingstudio/nasm,techkey/nasm,projedi/nasm,letolabs/nasm,techkey/nasm,turingstudio/nasm