build: if QRTR enabled the pkg-config should publicly require libqrtr-glib
When the QRTR support is enabled the qmi-glib.pc file should include 'qrtr-glib' as a public requirement instead of a private one, so that projects building against libqmi can also detect where the libqrtr-glib headers are available (given that 'qmi-device.h' includes 'libqrtr-glib.h').
Before the change the dependencies in the pkg-config looked like this: Requires: glib-2.0 >= 2.56, gobject-2.0, gio-2.0 Requires.private: qrtr-glib >= 1.0.0, gio-unix-2.0, mbim-glib >= 1.18.0
And now they look like this: Requires: glib-2.0 >= 2.56, gobject-2.0, gio-2.0, qrtr-glib >= 1.0.0 Requires.private: gio-unix-2.0, mbim-glib >= 1.18.0
Fixes #99 (closed)