Not a favorable solution, since this is probably some outdated quirk to begin
with. But in life, shall we leave the unknown to itself...

diff '--color=auto' -ru NetHack-3.6.7/win/tty/termcap.c NetHack-3.6.7-fix/win/tty/termcap.c
--- NetHack-3.6.7/win/tty/termcap.c	2026-03-29 17:22:57.252478012 -0400
+++ NetHack-3.6.7-fix/win/tty/termcap.c	2026-03-29 18:36:03.070723420 -0400
@@ -838,7 +838,7 @@
 
 #include <curses.h>
 
-#if !defined(LINUX) && !defined(__FreeBSD__) && !defined(NOTPARMDECL)
+#if !defined(__gnu_hurd__) && !defined(LINUX) && !defined(__FreeBSD__) && !defined(NOTPARMDECL)
 extern char *tparm();
 #endif