common-main: call git_setup_gettext()

This should be part of every program, as otherwise users do
not get translated error messages. However, some external
commands forgot to do so (e.g., git-credential-store). This
fixes them, and eliminates the repeated code in programs
that did remember to use it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

shell.c

@@ -145,8 +145,6 @@ int cmd_main(int argc, const char **argv)
 	struct commands *cmd;
 	int count;
 
-	git_setup_gettext();
-
 	/*
 	 * Special hack to pretend to be a CVS server
 	 */