Use atexit to fix finalizers on Windows #1361.

resources/examples/ls.c3

@@ -2,8 +2,8 @@ import std::io;
 
 fn void main()
 {
-	Path path = path::getcwd()!!;
-	foreach (i, p : path::ls(path)!!)
+	Path path = path::new_cwd()!!;
+	foreach (i, p : path::new_ls(path)!!)
 	{
 		io::printfn("%02d %s", i, p.str_view());
 	}

resources/msvc_stack.c3

@@ -2,6 +2,12 @@ module test;
 import std::io;
 import std::collections::map;
 import std::os;
+import libc;
+
+fn void bye() @finalizer
+{
+	libc::puts("Bye from finalizer!");
+}
 
 fn void test1()
 {