I picked it here:
https://bugs.archlinux.org/task/23915

--- qt-x11-free-3.3.8b/src/tools/qmap.h~	2008-01-15 19:09:13.000000000 +0000
+++ qt-x11-free-3.3.8b/src/tools/qmap.h	2011-04-11 00:16:04.000000000 +0100
@@ -50,6 +50,7 @@
 #endif // QT_H
 
 #ifndef QT_NO_STL
+#include <cstddef>
 #include <iterator>
 #include <map>
 #endif
--- qt-x11-free-3.3.8b/src/tools/qvaluelist.h~	2008-01-15 19:09:13.000000000 +0000
+++ qt-x11-free-3.3.8b/src/tools/qvaluelist.h	2011-04-11 00:16:49.000000000 +0100
@@ -48,6 +48,7 @@
 #endif // QT_H
 
 #ifndef QT_NO_STL
+#include <cstddef>
 #include <iterator>
 #include <list>
 #endif