Unix Makefile.utl wasn't aware of the dependency of makedefs.o on
src/mdlib.c so didn't rebuild makedefs when it should have.
Eliminate several warnings:
mdlib.c - #if inside the arguments to macro Sprintf();
nhlua.c - nhl_error() ends with a call to lua_error() which doesn't
return, but neither of them were declared that way;
nhlsel.c - because of the previous, the 'else error' case of
l_selection_ellipse() led to complaints about uninitialized
variables;
sp_lev.c - missing 'const'.
I did minimal testing which went ok, but revisiting a couple of levels
gave me un-freed memory allocated by restore.c line 1337. (I haven't
looked at that at all.)