Remove unused Qt 4.6 patch.

Core no longer supports Qt 4. Therefore, the STL fix patch isn't needed.

depends/patches/qt46/stlfix.patch

@@ -1,10 +0,0 @@
---- old/config.tests/unix/stl/stltest.cpp	2011-06-23 03:45:23.000000000 -0400
-+++ new/config.tests/unix/stl/stltest.cpp	2014-08-28 00:54:04.154837604 -0400
-@@ -49,6 +49,7 @@
- #include <vector>
- #include <algorithm>
- #include <iostream>
-+#include <cstddef>
- 
- // something mean to see if the compiler and C++ standard lib are good enough
- template<class K, class T>