Resurrect peek-remote

8951d7c1f1 (Build in ls-remote) made
peek-remote as a synonym to ls-remote by enhancing the latter, but
at the same time actually _removed_ it, before we officially gave
removal notice.  This was bad.

Resurrect it for v1.5.4.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -259,7 +259,7 @@ EXTRA_PROGRAMS =
 BUILT_INS = \
 	git-format-patch$X git-show$X git-whatchanged$X git-cherry$X \
 	git-get-tar-commit-id$X git-init$X git-repo-config$X \
-	git-fsck-objects$X git-cherry-pick$X \
+	git-fsck-objects$X git-cherry-pick$X git-peek-remote$X \
 	$(patsubst builtin-%.o,git-%$X,$(BUILTIN_OBJS))
 
 # what 'all' will build and 'install' will install, in gitexecdir