support for build with current Lua version 5.4.2

This may require
    	make spotless
    	make fetch-lua
for some platforms.

sys/winnt/travis-gcc.sh

@@ -3,6 +3,6 @@ mkdir -p lib
 cd lib
 git clone --depth 1 https://github.com/wmcbrine/PDCurses.git pdcurses
 #git clone --depth 1 https://github.com/universal-ctags/ctags.git ctags
-curl -R -O http://www.lua.org/ftp/lua-5.4.1.tar.gz
-tar zxf lua-5.4.1.tar.gz
+curl -R -O http://www.lua.org/ftp/lua-5.4.2.tar.gz
+tar zxf lua-5.4.2.tar.gz
 cd ../