Include paths passed to configure script are not passed into build

As per the thread at http://qt-project.org/forums/viewthread/35998/ :

I pass a path to the configure script thus “-I /opt/local/include”. This path, in conjunction with the flag “-icu”, allows detection and successful activation of the ICU feature by configure.

When the time comes to build, though, this path is not added to the compilation lines. The build therefore fails since the ICU headers cannot be found.

Happy to duplicate content of that forum thread into this bug if that's deemed appropriate.