to avoid

CCLD     storagevolxml2argvtest
/usr/bin/ld: ../src/.libs/libvirt_driver_storage_impl.a(libvirt_driver_storage_impl_la-storage_backend.o): undefined reference to symbol 'xmlFreeDoc@@LIBXML2_2.4.30'
//usr/lib/x86_64-linux-gnu/libxml2.so.2: error adding symbols: DSO missing from command line