If you do

$ pkg-config --cflags Qt5Widgets

you get

-I/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/include/QtWidgets -I/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/include -I/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/include/QtGui -I/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/include -I/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/include/QtCore -I/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/include

which doesn't treat Qt as a framework.

If you do

$ pkg-config --libs Qt5Widgets

you get

-F/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/lib -framework QtWidgets -F/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/lib -framework QtGui -F/Users/gharris/Qt5.2.0/5.2.0-rc1/clang_64/lib -framework QtCore

which does treat it as a framework.

The same applies for Qt5Core, and probably other components.

This means that autoconf-based projects (such as Wireshark) don't find the header files when you try to build them.