rework Windows build instructions

sys/windows/fetch.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+
+if [ ! -d lib ]; then
+mkdir -p lib
+fi
+
+if [ $1 == "lua" ]; then
+ if [ -z "$LUA_VERSION" ]; then
+ export LUA_VERSION=5.4.6
+ export LUASRC=../lib/lua
+ fi
+
+ export CURLLUASRC=http://www.lua.org/ftp/lua-5.4.6.tar.gz
+ export CURLLUADST=lua-5.4.6.tar.gz
+
+ if [ ! -f lib/lua.h ] ;then
+	cd lib
+	curl -L $CURLLUASRC -o $CURLLUADST
+	/c/Windows/System32/tar -xvf $CURLLUADST
+	cd ..
+ fi
+fi
+
+if [ $1 == "pdcursesmod" ]; then
+ export CURLPDCSRC=https://github.com/Bill-Gray/PDCursesMod/archive/refs/tags/v4.4.0.zip
+ export CURLPDCDST=pdcursesmod.zip
+
+ if [ ! -f lib/pdcursesmod/curses.h ] ; then
+	cd lib
+	curl -L $CURLPDCSRC -o $CURLPDCDST
+	/c/Windows/System32/tar -xvf $CURLPDCDST
+	mkdir -p pdcursesmod
+	/c/Windows/System32/tar -C pdcursesmod --strip-components=1 -xvf $CURLPDCDST
+	cd ..
+ fi
+fi