sim: punt zfree()

sim: punt zfree()

The sim keeps track of which allocations are zero-ed internally (via
zalloc) and then calls a helper "zfree" function rather than "free".
But this "zfree" function simply calls "free" itself.  Since I can
see no point in this and it is simply useless overhead, punt it.

The only real change is in hw-alloc.c where we remove the zalloc_p
tracking, and sim-utils.c where zfree is delete.  The rest of the
changes are a simple `sed` from "zfree" to "free".

Signed-off-by: Mike Frysinger <vapier@gentoo.org>