test: include qemuhotplugtest data files in source rpm

commit 0fc12bca added a new test called qemuhotplugtest which has
several data files in tests/qemuhotplugtestdata, but didn't add that
directory to EXTRA_DIST in the tests Makefile.am, so the make check
done during a make rpm was failing due to missing data files.

tests/Makefile.am

@@ -80,6 +80,7 @@ EXTRA_DIST =		\
 	nwfilterxml2xmlout \
 	oomtrace.pl \
 	qemuhelpdata \
+	qemuhotplugtestdata \
 	qemuxml2argvdata \
 	qemuxml2xmloutdata \
 	qemuxmlnsdata \