include: Handle case when builddir == srcdir

In my previous commit a70f3b1c I've tried to fix case
when building from VPATH and a file wasn't being installed.
However, my fix broke non-VPATH build.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
(cherry picked from commit 0d0e41a7)
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

include/Makefile.am

@@ -19,7 +19,8 @@
 virincdir = $(includedir)/libvirt
 
 allheaders = $(wildcard $(srcdir)/libvirt/*.h)
-virinc_HEADERS = $(filter-out $(srcdir)/libvirt/libvirt-admin.h, $(allheaders))
+virinc_HEADERS = $(filter-out $(srcdir)/libvirt/libvirt-admin.h \
+				 $(srcdir)/libvirt/libvirt-common.h, $(allheaders))
 virinc_HEADERS += libvirt/libvirt-common.h
 
 EXTRA_DIST = libvirt/libvirt-common.h.in