preproc: correct handling of %ifdef for aliases
preproc: correct handling of %ifdef for aliases

Correctly handling %ifdef when operating on aliases; we had an
infinite loop going...

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

techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm