Correct SIZE_T size according to MS SDK.
Change some types to SIZE_T according to MS SDK definitions.

diff --git a/scheduler/thread.c b/scheduler/thread.c
index 574324c..eb5fe60 100644
--- a/scheduler/thread.c
+++ b/scheduler/thread.c
@@ -271,7 +271,7 @@
 /***********************************************************************
  *           CreateThread   (KERNEL32.@)
  */
-HANDLE WINAPI CreateThread( SECURITY_ATTRIBUTES *sa, DWORD stack,
+HANDLE WINAPI CreateThread( SECURITY_ATTRIBUTES *sa, SIZE_T stack,
                             LPTHREAD_START_ROUTINE start, LPVOID param,
                             DWORD flags, LPDWORD id )
 {