Produce more verbose error if cppi not found
Produce more verbose error if cppi not found

It's fairly easy (especially for new contributors) to not spot
the 'cppi not installed' line in the syntax-check output. Add a
banner that is shown at the end of syntax-check output if no cppi
was found.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
ACKed-by: Andrea Bolognani <3ada0bee826c753786fdbba72243dfba997094cf@redhat.com>

libvirt/libvirt,fabianfreyer/libvirt,crobinso/libvirt,libvirt/libvirt,crobinso/libvirt,olafhering/libvirt,jardasgit/libvirt,zippy2/libvirt,fabianfreyer/libvirt,olafhering/libvirt,eskultety/libvirt,jfehlig/libvirt,jfehlig/libvirt,andreabolognani/libvirt,jardasgit/libvirt,zippy2/libvirt,olafhering/libvirt,nertpinx/libvirt,zippy2/libvirt,nertpinx/libvirt,libvirt/libvirt,andreabolognani/libvirt,eskultety/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,libvirt/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,zippy2/libvirt,jfehlig/libvirt,crobinso/libvirt,jardasgit/libvirt,nertpinx/libvirt,nertpinx/libvirt,andreabolognani/libvirt,olafhering/libvirt,fabianfreyer/libvirt,eskultety/libvirt,jfehlig/libvirt,andreabolognani/libvirt,jardasgit/libvirt,eskultety/libvirt,andreabolognani/libvirt,eskultety/libvirt,crobinso/libvirt