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/npm-package/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "@neth4ck/neth4ck",
+  "version": "1.0.0",
+  "description": "The original NetHack rogue-like game built as a WebAssembly module",
+  "main": "src/nethackShim.js",
+  "scripts": {
+    "test": "node test/test.js",
+    "clean": "rm ./build/nethack.js; rm ./build/nethack.wasm; true",
+    "build": "cp ../../../src/nethack.js ../../../src/nethack.wasm ./build",
+    "prepack": "npm run build"
+  },
+  "keywords": [
+    "nethack",
+    "rogue",
+    "rogue-like",
+    "game"
+  ],
+  "author": "Adam Powers <apowers@ato.ms>",
+  "license": "SEE LICENSE IN LICENSE.md"
+}