grep: fix some memory leaks.

Bring a couple of changes from NetBSD:

queue.c (CVS Rev. 1.4. 1.5)
Fix memory leaks.
NULL does not need a cast.

grep.c (CVS Rev. 1.6)
Use the more portable getline.

Obtained from:	NetBSD
MFC after:	3 days
Fix indentation
grep: fix some memory leaks.
Add memory leak fix missing from r268799.

Obtained from:	NetBSD