Revert "Added nhassert to core."

This reverts commit 0ca299acb3.

include/ntconf.h

@@ -267,6 +267,16 @@ extern int FDECL(set_win32_option, (const char *, const char *));
 extern int FDECL(alternative_palette, (char *));
 #endif
 
+#ifdef NDEBUG
+#define nhassert(expression) ((void)0)
+#else
+extern void FDECL(nhassert_failed, (const char * exp, const char * file,
+                                    int line));
+
+#define nhassert(expression) (void)((!!(expression)) || \
+        (nhassert_failed(#expression, __FILE__, __LINE__), 0))
+#endif
+
 #define nethack_enter(argc, argv) nethack_enter_winnt()
 extern void FDECL(nethack_exit, (int)) NORETURN;
 extern boolean FDECL(file_exists, (const char *));