Implement the rename query, for when a file with the same name as the one

Implement the rename query, for when a file with the same name as the one
about to be extracted already exists.  The question, and interpretation
of the response is deliberately compatible with Info-Zip.

This change was originally obtained from NetBSD, but has three changes:
 - better compatibility with Info-Zip in the handling of ^D
 - Use getdelim() rather than getline()
 - bug fix: != changed to == in the "file rename" code

I suspect the latter is also a bug in NetBSD, but I can't easily confirm
this.

PR:		bin/143307
Reviewed by:	rdivacky (change to unzip.c only)
Obtained from:	NetBSD src/usr.bin/unzip/unzip.c 1.8
MFC after:	1 month