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.

sys/lib/test/run.sh

@@ -0,0 +1,41 @@
+#!/bin/bash -x
+
+if [ x$1 == "xlib" ]; then
+    echo Doing lib...
+    make spotless
+    cd sys/lib
+    ./setup.sh hints/macOS.2020
+    cd ../..
+    make
+fi
+
+if [ x$1 == "xrunlib" ]; then
+    LIBS="-Lsrc -lnethack -Llib/lua -llua -lm"
+    BADLIBS="-lncurses"
+    rm nhlibtest
+    gcc -o nhlibtest libtest.c $LIBS $BADLIBS
+    ./nhlibtest
+fi
+
+if [ x$1 == "xwasm" ]; then
+    echo Doing wasm...
+    make spotless
+    cd sys/lib
+    ./setup.sh hints/wasm
+    cd ../..
+    make
+fi
+
+if [ x$1 == "xrunwasm" ]; then
+    cd sys/lib/npm-package && node test/test.js
+fi
+
+if [ x$1 == "xbin" ]; then
+    echo Doing bin...
+    make spotless
+    cd sys/unix
+    ./setup.sh hints/macOS.2020
+    cd ../..
+    make
+fi
+