luck artifact dependencies

Instead of adding a new artifact.h to pray.c, remove the existing
ones from attrib.c, invent.c, and mkobj.c.  This also updates the Unix
and VMS editions of Makefile.src; having stale dependencies in those
for other ports could cause unnecessary recompilation but can't break
anything in this case.

src/artifact.c

@@ -248,6 +248,17 @@ unsigned long abil;
 	return((boolean)(arti && (arti->spfx & abil)));
 }
 
+/* used so that callers don't need to known about SPFX_ codes */
+boolean
+confers_luck(obj)
+struct obj *obj;
+{
+    /* might as well check for this too */
+    if (obj->otyp == LUCKSTONE) return TRUE;
+
+    return (obj->oartifact && spec_ability(obj, SPFX_LUCK));
+}
+
 #endif /* OVL0 */
 #ifdef OVLB