git-sh-setup.sh: remove "say" function, change last users

Remove the "say" function, with various rewrites of the remaining
git-*.sh code to C and the preceding change to have git-submodule.sh
stop using the GIT_QUIET variable there were only four uses in
git-subtree.sh. Let's have it use an "arg_quiet" variable instead, and
move the "say" function over to it.

The only other use was a trivial message in git-instaweb.sh, since it
has never supported the --quiet option (or similar) that code added in
0b624b4cee (instaweb: restart server if already running, 2009-11-22)
can simply use "echo" instead.

The remaining in-tree hits from "say" are all for the sibling function
defined in t/test-lib.sh. It's safe to remove this function since it
has never been documented in Documentation/git-sh-setup.txt.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-instaweb.sh

@@ -102,7 +102,7 @@ resolve_full_httpd () {
 
 start_httpd () {
 	if test -f "$fqgitdir/pid"; then
-		say "Instance already running. Restarting..."
+		echo "Instance already running. Restarting..."
 		stop_httpd
 	fi