includes: Install libvirt-common.h

includes: Install libvirt-common.h

The libvirt-common.h is build time generated file from .in.
Obviously, it's generated into builddir and not srcdir. Problem
is, the list of header files to install, virinc_HEADERS contains
only $(srcdir)/*.h and this misses libvirt-common.h. This problem
is pretty obvious when doing a VPATH build.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
(cherry picked from commit a70f3b1c77912012905c6c5be3bf37b05592e80f)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>