runtime error passing fp 

I needed to make this change for a debug windows 64 build of slicer4.  Without this, slicer crashes at startup (probably due to mix debug/release dlls).

https://github.com/pieper/PythonQt/commit/fa92a77c8fae6d96dba4876b5f51a4fe9317bf77
