make each -devel package install only its own headers

Currently both qtbluetooth-devel and qtnfc-devel packages get a copy of all of each others development headers and pkgconfig files. That is, qtnfc-devel contains both qtnfc.pc AND qtbluetooth.pc. Same for qtbluetooth-devel.

This causes confusion when resolving pkgconfig(qtbluetooth), e.g.

    have choice for pkgconfig(Qt5Bluetooth): qt5-qtconnectivity-qtbluetooth-devel qt5-qtconnectivity-qtnfc-devel

This patch fixes the .spec file so that each package gets only its own headers and pkgconfig files.

Note: Haven't been able to test this change on the Qt5.2 branch, but it worked on previous Sailfish (Qt5.1) versions.