preproc: do_directive: Allocate 'Include' from zeroified-memory
If not all members of structure being allocated from
heap get initialized we better to use nasm_zalloc instead
of nasm_malloc.
For example inc gets allocated in do_directive being parially
initialized and we erroniously get mmac_depth set to some
crappy value leading to SIGSEV in result.
[ http://forum.nasm.us/index.php?topic=921.msg3257#msg3257 ]
nb: I've cleaned verror from tab/space mess while were at it
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>