po: fix conflict with %.mo rule in rules.mak

po/Makefile includes rules.mak to use the nice quiet-command macro.
However, this also brings in a %.mo rule that breaks "make build".
Put our own rule before the include, so that it has precedence.
Reported-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

po/Makefile

@@ -9,6 +9,9 @@ all:
 
 .PHONY:	all build clean install update
 
+%.mo: %.po
+	$(call quiet-command, msgfmt -o $@ $<, "  GEN   $@")
+
 -include ../config-host.mak
 include $(SRC_PATH)/rules.mak
 
@@ -38,9 +41,6 @@ install: $(OBJS)
 	    $(INSTALL) -m644 $$obj $(DESTDIR)$(prefix)/share/locale/$$base/LC_MESSAGES/qemu.mo; \
 	done
 
-%.mo: %.po
-	$(call quiet-command, msgfmt -o $@ $<, "  GEN   $@")
-
 $(PO_PATH)/messages.po: $(SRC_PATH)/ui/gtk.c
 	$(call quiet-command, ( cd $(SRC_PATH) && \
           xgettext -o - --from-code=UTF-8 --foreign-user \