genrand.c: Changed SMB_PASSWD_FILE to lp_smb_passwd_file().

genrand.c: Changed SMB_PASSWD_FILE to lp_smb_passwd_file().
password.c: Started the initial code for domain_client_validate(). All
            bracketed with #ifdef DOMAIN_CLIENT for now.
reply.c: Call to domain_client_validate(). All
            bracketed with #ifdef DOMAIN_CLIENT for now.
smbpass.c: New code to get/set machine passwords. Tidied up nesting
           of lock calls.
Jeremy.
(This used to be commit 89fe059a6816f32d2cc5c4c04c4089b60590e7e6)