fix nhl_loadlua() failures on Windows

The [dlb_]fopen() requires an RDBMODE argument on Windows.
ftell(), fseek(), and fread() interactions can be problematic otherwise.

doc/fixes37.0

@@ -804,6 +804,9 @@ Unix: after lua changes to Makefiles, 'make spotless' for dat subdirectory
 	left some generated data files which should have been deleted
 Windows: new tile additions in win/share did not trigger the creation of a new
 	NetHackW.res file
+Windows: nhl_loadlua() was missing the RDBMODE argument on the [dlb_]fopen()
+	that is necessary to ensure binary mode for navigating around a file
+ 	with fseek(), ftell() and fread() reliably
 X11: was still initializing map to 'stone' instead of 'unexplored' after they
 	became separate glyphs
 X11: for text map without color, add support for black&white ice; draw it in

src/nhlua.c

@@ -1244,7 +1244,7 @@ nhl_loadlua(lua_State *L, const char *fname)
        if we did, we could choose between "nhdat(<fname>)" and "<fname>"
        but since we don't, compromise */
     Sprintf(altfname, "(%s)", fname);
-    fh = dlb_fopen(fname, "r");
+    fh = dlb_fopen(fname, RDBMODE);
     if (!fh) {
         impossible("nhl_loadlua: Error loading %s", altfname);
         ret = FALSE;