tools: fetch remote changesets when force refetching/resetting qemu

This makes "make tools/ioemu-dir-force-update" usable for picking up
an entirely new QEMU_TAG.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/Makefile

@@ -117,6 +117,7 @@ ioemu-dir-force-update:
 	set -ex; \
 	if [ "$(QEMU_TAG)" ]; then \
 		cd ioemu-remote; \
+		$(GIT) fetch origin; \
 		$(GIT) reset --hard $(QEMU_TAG); \
 	fi