libnethack pr385

roll parts of pr385 into source tree

This does not take the PR as is.

Unlike the PR, this streamlines and minimizes the integration somewhat:

- use hints/include mechanism instead of creating alternative
  Makefile.dat, Makefile.src, Makefile.top, Makefile.utl in sys/lib;
  those would have been a maintenance nightmare.

- don't have alternative mkmkfile.sh and setup.sh in sys/lib.

- sys/lib/libnethackmain.c differed from sys/unix/unixmain.c by
  very little, so just place a small bit of conditional code at the
  top of sys/unix/unixmain.c instead.

- changed the conditional code bits from __EMSCRIPTEN__ to
  CROSS_TO_WASM.

- You should be able to build the wasm result by:
    cd sys/unix ; sh setup.sh hints/linux.2020 ; cd ../..
    make fetch-lua    (<-one time)
    make WANT_LIBNH all

- You should be able to build LIBNBH by:
    cd sys/unix ; sh setup.sh hints/linux.2020 ; cd ../..
    make fetch-lua    (<-one time)
    make CROSS_TO_WASM=1 all

As it is currently coded, winshim.c requires C99.

include/global.h

@@ -399,11 +399,14 @@ struct savefile_info {
 #ifdef UNIX
 #if (NH_DEVEL_STATUS != NH_STATUS_RELEASED)
 /* see end.c */
+#if !defined(CROSS_TO_WASM)
 #ifndef PANICTRACE
 #define PANICTRACE
-#endif
-#endif
-#endif
+#endif  /* PANICTRACE */
+#endif  /* CROSS_TO_WASM */
+#endif  /* NH_DEVEL_STATUS != NH_STATUS_RELEASED */
+#endif  /* UNIX */
+
 /* The following are meaningless if PANICTRACE is not defined: */
 #if defined(__linux__) && defined(__GLIBC__) && (__GLIBC__ >= 2)
 #define PANICTRACE_LIBC
@@ -412,8 +415,10 @@ struct savefile_info {
 #define PANICTRACE_LIBC
 #endif
 #ifdef UNIX
+#if !defined(CROSS_TO_WASM) /* no popen in WASM */
 #define PANICTRACE_GDB
 #endif
+#endif
 
 /* Supply nethack_enter macro if not supplied by port */
 #ifndef nethack_enter

include/unixconf.h

@@ -389,7 +389,7 @@
 #endif /* LINUX */
 #endif /* GNOME_GRAPHICS */
 
-#ifdef MACOSX
+#if defined(MACOSX) && !defined(LIBNH)
 # define RUNTIME_PASTEBUF_SUPPORT
 #endif