http-fetch: Fix Makefile dependancies

Specify git-http-fetch's dependancies explicitly rather than inheriting from
git-http-push, as that may not be built if the libcurl version is too old or
NO_EXPAT is defined

Signed-off-by: Mike Ralphson <mike@abacus.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -1487,7 +1487,7 @@ http.o http-walker.o http-push.o: http.h
 
 http.o http-walker.o: $(LIB_H)
 
-git-http-fetch$X: revision.o http.o http-push.o $(GITLIBS)
+git-http-fetch$X: revision.o http.o http-walker.o http-fetch.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
 		$(LIBS) $(CURL_LIBCURL) $(EXPAT_LIBEXPAT)
 git-http-push$X: revision.o http.o http-push.o $(GITLIBS)