Reimplement the Windows OS dependencies in package runtime

core/runtime/os_specific_freestanding.odin

@@ -1,15 +1,8 @@
 //+build freestanding
 package runtime
 
-_OS_Errno  :: distinct int;
-_OS_Handle :: distinct uintptr;
-
-os_stderr :: proc "contextless" () -> _OS_Handle {
-	return 2;
-}
-
 // TODO(bill): reimplement `os.write`
-os_write :: proc(fd: _OS_Handle, data: []byte) -> (int, _OS_Errno) {
+os_write :: proc "contextless" (data: []byte) -> (int, _OS_Errno) {
 	return 0, -1;
 }