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/hints/wasm

@@ -0,0 +1,77 @@
+
+#-PRE xxxx
+# enscripten WebAssembly config
+
+WANT_WASM=1
+WASM_DEBUG=1
+WASM_DATA_DIR=$(NHSROOT)/src/wasm-data
+
+# toolchain
+EMCC=emcc
+EMAR=emar rcu
+EMRANLIB=emranlib
+
+# link flags
+EMCC_LFLAGS=-s SINGLE_FILE=1
+EMCC_LFLAGS=-s WASM=1
+EMCC_LFLAGS+=-s ALLOW_TABLE_GROWTH
+EMCC_LFLAGS+=-s ASYNCIFY -s ASYNCIFY_IMPORTS='["local_callback"]'
+EMCC_LFLAGS+=-O3
+EMCC_LFLAGS+=-s MODULARIZE
+EMCC_LFLAGS+=-s EXPORTED_FUNCTIONS='["_main", "_shim_graphics_set_callback"]'
+EMCC_LFLAGS+=-s EXPORTED_RUNTIME_METHODS='["cwrap", "ccall", "addFunction", "removeFunction", "UTF8ToString", "getValue", "setValue"]'
+EMCC_LFLAGS+=-s ERROR_ON_UNDEFINED_SYMBOLS=0
+EMCC_LFLAGS+=--embed-file wasm-data@/
+
+# For a list of EMCC settings:
+# https://github.com/emscripten-core/emscripten/blob/master/src/settings.js
+
+# WASM C flags
+EMCC_CFLAGS=
+EMCC_CFLAGS+=-Wall
+EMCC_CFLAGS+=-Werror
+#EMCC_CFLAGS+=-s DISABLE_EXCEPTION_CATCHING=0
+EMCC_DEBUG_CFLAGS+=-s ASSERTIONS=1
+#EMCC_DEBUG_CFLAGS+=-s ASSERTIONS=2
+EMCC_DEBUG_CFLAGS+=-s STACK_OVERFLOW_CHECK=2
+EMCC_DEBUG_CFLAGS+=-s SAFE_HEAP=1
+EMCC_DEBUG_CFLAGS+=-s LLD_REPORT_UNDEFINED=1
+#EMCC_DEBUG_CFLAGS+=-s EXCEPTION_DEBUG=1
+#EMCC_DEBUG_CFLAGS+=-fsanitize=undefined -fsanitize=address -fsanitize=leak
+#EMCC_DEBUG_CFLAGS+=-s EXIT_RUNTIME
+EMCC_PROD_CFLAGS+=-O3
+
+# Nethack C flags
+CFLAGS+=-DSYSCF -DSYSCF_FILE=\"/sysconf\" -DSECURE
+CFLAGS+=-g -I../include -DNOTPARMDECL
+CFLAGS+=-Wall
+CFLAGS+=-Werror
+CFLAGS+=-DGCC_WARN
+
+# NetHack sources control
+CFLAGS+=-DDLB
+CFLAGS+=-DHACKDIR=\"$(HACKDIR)\"
+CFLAGS+=-DDLB
+#CFLAGS+=-DGREPPATH=\"/usr/bin/grep\"
+CFLAGS+=-DNOMAIL
+
+ifdef WASM_DEBUG
+EMCC_CFLAGS+=$(EMCC_DEBUG_CFLAGS)
+else
+EMCC_CFLAGS+=$(EMCC_PROD_CFLAGS)
+endif
+
+# installation config
+# hackdir is the wasm / emscripten embed data root directory
+HACKDIR=/
+CHOWN=/usr/bin/true
+CHGRP=/usr/bin/true
+GAMEPERM = 0700
+VARFILEPERM = 0600
+VARDIRPERM = 0700
+
+INSTDIR=$(HACKDIR)
+VARDIR=$(HACKDIR)
+
+#-POST
+# no post