MFC	r267426, r267464:

Avoid zeroing during allocation.

This change reverts a change from OpenBSD which made use of
calloc, and therefore wasted time initializing arrays that
will later be realloc'ed.

Consistently use FreeBSD's reallocf():
- Drop some bogus casts to size_t.
- The new_p_foo variables are not needed anymore.

Also merge the changes from OpenBSD's manpage
patch.1 Rev 1.27:
"patch was moved from user portability (UP) to base in issue 7
and is no longer optional"