[Samba] samba 2.2.8a bug: misc. tdb compile problems on SunOS 4.x

[David DiGiacomo]

1. tdb/tdb.c and tdb/tdb.h use sig_atomic_t instead of SIG_ATOMIC_T

2. tdbbackup.c doesn't include "includes.h"

3. tdb.c uses memmove(), but tdbbackup doesn't link with lib/replace.o