remove usage of bzero

remove usage of bzero

bzero() function has been deprecated for a long time.
In samba it is replaced with memset().  But samba also
provides common memory-zeroing macros, like ZERO_STRUCT().
In all places where bzero() is used, it actually meant to
zero a structure or an array.

So replace these bzero() calls with ZERO_STRUCT() or
ZERO_ARRAY() as appropriate, and remove bzero() replacement
and testing entirely.

While at it, also stop checking for presence of memset() -
this function is standard for a very long time, and the
only conditional where HAVE_MEMSET were used, was to
provide replacement for bzero() - in all other places
memset() is used unconditionally.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Pavel Filipenský <pfilipensky@samba.org>