Makefile: remove dependency on git.spec

ab214331 (Makefile: stop pretending to support rpmbuild, 2016-04-04)
dropped support for rpmbuild using our own specfile by removing
git.spec.in, but forgot to remove the dependency of the dist target
on git.spec.

Signed-off-by: Dennis Kaarsemaker <dennis@kaarsemaker.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -2396,7 +2396,7 @@ quick-install-html:
 ### Maintainer's dist rules
 
 GIT_TARNAME = git-$(GIT_VERSION)
-dist: git.spec git-archive$(X) configure
+dist: git-archive$(X) configure
 	./git-archive --format=tar \
 		--prefix=$(GIT_TARNAME)/ HEAD^{tree} > $(GIT_TARNAME).tar
 	@mkdir -p $(GIT_TARNAME)