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/unix/Makefile.src

@@ -300,6 +300,12 @@ WINGNOMEOBJ =
 WINGEMSRC =
 WINGEMOBJ =
 
+# Files for Shim windowing interface for libnethack -- doesn't do anything,
+# just passes along the API calls to the library
+#
+WINSHIMSRC = ../win/shim/winshim.c
+WINSHIMOBJ = winshim.o
+
 #
 # Files for a BeOS InterfaceKit port -- not ready for prime time
 WINBESRC =
@@ -524,7 +530,7 @@ SYSCXXSRC = ../sys/share/cppregex.cpp
 GENCSRC = vis_tab.c	#tile.c
 
 # all windowing-system-dependent .c (for dependencies and such)
-WINCSRC = $(WINTTYSRC) $(WINCURSESSRC) $(WINX11SRC) $(WINGNOMESRC) $(WINGEMSRC)
+WINCSRC = $(WINTTYSRC) $(WINCURSESSRC) $(WINX11SRC) $(WINGNOMESRC) $(WINGEMSRC) $(WINSHIMSRC)
 # all windowing-system-dependent .cpp (for dependencies and such)
 WINCXXSRC = $(WINQTSRC) $(WINQT3SRC) $(WINBESRC)