support for build with current Lua version 5.4.2

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

sys/msdos/fetch-cross-compiler.sh

@@ -12,7 +12,7 @@ if [ -z "$GCCVER" ]; then
 fi
 
 if [ -z "$LUA_VERSION" ]; then
-	export LUA_VERSION=5.4.1
+	export LUA_VERSION=5.4.2
 fi
 
 if [ ! -d "$(pwd)/lib" ]; then