tests: Distribute virpcitestdata

Since 21685c95 we have tests/virpcitestdata dir containing the PCI
config files for some dummy PCI devices that are used int virpcitest.
However, the directory containing the config files is not distributed
making 'make rpm' fail.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

tests/Makefile.am

@@ -107,6 +107,7 @@ EXTRA_DIST =		\
 	sysinfodata \
 	test-lib.sh	\
 	virsh-uriprecedence \
+	virpcitestdata \
 	vmx2xmldata \
 	xencapsdata \
 	xmconfigdata \