build: list sources of lib pdb directly in def, removing vars=locals()

build: list sources of lib pdb directly in def, removing vars=locals()

Also, remove a comment
"#FIXME: lib/winbind_util.c probably is not part of PASSDB_SRC"
while moving he list:
lib/winbind_util.c is in fact a winbind wrapper for passdb.

Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>