tests: Add storagepoolxml2argvtest source to EXTRA_DIST

Commit f2f84b4d added storagepoolxml2argvtest processing; however,
it didn't follow alter the else to !WITH_STORAGE and add the source
itself to the EXTRA_DIST like the other WITH_STORAGE options for
virstorageutiltest and storagevolxml2argvtest.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
ACKed-by: NMichal Privoznik <mprivozn@redhat.com>

tests/Makefile.am

@@ -935,6 +935,7 @@ storagepoolxml2xmltest_LDADD = $(LDADDS) \
 else ! WITH_STORAGE
 EXTRA_DIST += storagevolxml2argvtest.c
 EXTRA_DIST += virstorageutiltest.c
+EXTRA_DIST += storagepoolxml2argvtest.c
 EXTRA_DIST += storagepoolxml2xmltest.c
 endif ! WITH_STORAGE