Explicitly include stddef.h for offsetof, needed for newer GCC versions

svn path=/trunk/; revision=8698

reactos/lib/comctl32/listview.c

@@ -147,6 +147,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <string.h>
+#include <stddef.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>

reactos/lib/ole32/oleproxy.c

@@ -35,6 +35,7 @@
 
 #include <stdlib.h>
 #include <stdarg.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>