nethack: Support cross compilation

Major caveat: x11 and qt don't work.

The main idea is to update the Makefiles with references to the correct
toolchain by replacing direct executable names with references to the
appropriate environment variables.

We also update the makefiles to use tools from the buildPlatform's
version of Nethack. As part of this, we have to final the install phase
to install these as part of native builds.

Finally, we fix an issue with the wrapper script where it would use the
build platform's version of bash as opposed to the host platforms.

pkgs/by-name/ne/nethack/package.nix

@@ -7,6 +7,8 @@
   ncurses,
   gzip,
   less,
+  bash,
+  buildPackages,
   x11Mode ? false,
   qtMode ? false,
   libxaw,
@@ -140,6 +142,30 @@ stdenv.mkDerivation (finalAttrs: {
     sed -e '/define CHDIR/d' \
         -e '/define ENHANCED_SYMBOLS/d' \
         -i include/config.h
+    sed \
+      -e 's,AR=.*,AR := $(AR) rcu,' \
+      -e 's,RANLIB=.*,RANLIB := $(RANLIB),' \
+      -i lib/lua-5.4.8/src/Makefile
+    sed \
+      -e 's,AR =.*,AR := $(AR),' \
+      -i sys/unix/Makefile.src
+    ${lib.optionalString (stdenv.buildPlatform != stdenv.hostPlatform)
+      # If we're cross-compiling, replace the paths to the data generation tools
+      # with the ones from the build platform's nethack package, since we can't
+      # run the ones we've built here.
+      ''
+        sed \
+          -e 's, ../util/makedefs,,' \
+          -e 's,\t../util/makedefs,\t${buildPackages.nethack}/libexec/nethack/makedefs,' \
+          -e 's,\t../util/dlb,\t${buildPackages.nethack}/libexec/nethack/dlb,' \
+          -e 's,../util/dlb cf nhdat,${buildPackages.nethack}/libexec/nethack/dlb cf nhdat,' \
+          -e 's,pkg-config,$(PKG_CONFIG),' \
+          -i sys/unix/Makefile.*
+        sed \
+          -e 's,pkg-config,$(PKG_CONFIG),' \
+          -i sys/unix/hints/linux.500
+      ''
+    }
   '';
 
   configurePhase = ''
@@ -163,7 +189,7 @@ stdenv.mkDerivation (finalAttrs: {
 
     mkdir -p $out/bin
     cat <<EOF >$out/bin/nethack
-    #! ${stdenv.shell} -e
+    #! ${lib.getExe bash} -e
     PATH=${binPath}:\$PATH
 
     if [ ! -d ${userDir} ]; then
@@ -194,8 +220,12 @@ stdenv.mkDerivation (finalAttrs: {
     fi
     EOF
     chmod +x $out/bin/nethack
-    install -Dm 555 util/makedefs -t $out/libexec/nethack/
-    ${lib.optionalString (!(x11Mode || qtMode)) "install -Dm 555 util/dlb -t $out/libexec/nethack/"}
+    ${lib.optionalString (!x11Mode && !qtMode && (stdenv.buildPlatform == stdenv.hostPlatform))
+      ''
+      install -Dm 555 util/makedefs -t $out/libexec/nethack/
+      install -Dm 555 util/dlb -t $out/libexec/nethack/
+      ''
+    }
   '';
 
   desktopItems = lib.optionals (x11Mode || qtMode) [