Add missing dependencies to libdnf.pc
Add missing dependencies to libdnf.pc

In order to build things with libdnf properly leveraging
the pkgconfig definitions (with Meson, for example), the
pkgconfig file needs to properly declare its requirement
for libsolv and libsolvext, as well as SQLite for SWDB.

hughsie/libhif,hughsie/libhif,rpm-software-management/libdnf,Conan-Kudo/libhif,rpm-software-management/libdnf,rpm-software-management/libhif,Conan-Kudo/libhif,rpm-software-management/libhif,rpm-software-management/libhif,rpm-software-management/libdnf,Conan-Kudo/libhif,rpm-software-management/libdnf,hughsie/libhif,Conan-Kudo/libhif,hughsie/libhif,rpm-software-management/libhif