Fixed BlitzMax thread regstration on Win32.

BlitzMax created threads are already registered.

blitz.mod/blitz_thread.c

@@ -90,9 +90,6 @@ BBObject *bbThreadGetData( int index ){
 static DWORD curThreadTls;
 
 static DWORD WINAPI threadProc( void *p ){
-
-	GC_call_with_stack_base(bbRegisterGCThread, NULL);
-
 	BBThread *thread=p;
 	
 	TlsSetValue( curThreadTls,thread );
@@ -100,8 +97,6 @@ static DWORD WINAPI threadProc( void *p ){
 	BBObject * result = thread->proc( thread->data[0] );
 	thread->result = result;
 
-	GC_unregister_my_thread();
-
 	BB_LOCK
 	removeThread( thread );
 	BB_UNLOCK