http-backend.c: fix "dir" and "cmd_arg" leaks in cmd_main()

Free the "dir" variable after we're done with it. Before
917adc0360 (http-backend: add GIT_PROJECT_ROOT environment var,
2009-10-30) there was no leak here, as we'd get it via getenv(), but
since 917adc0360 we've xstrdup()'d it (or the equivalent), so we need
to free() it.

We also need to free the "cmd_arg" variable, which has been leaked
ever since it was added in 2f4038ab33 (Git-aware CGI to provide dumb
HTTP transport, 2009-10-30).

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

http-backend.c

@@ -786,6 +786,7 @@ int cmd_main(int argc, const char **argv)
 	if (!getenv("GIT_HTTP_EXPORT_ALL") &&
 	    access("git-daemon-export-ok", F_OK) )
 		not_found(&hdr, "Repository not exported: '%s'", dir);
+	free(dir);
 
 	http_config();
 	max_request_buffer = git_env_ulong("GIT_HTTP_MAX_REQUEST_BUFFER",
@@ -795,5 +796,6 @@ int cmd_main(int argc, const char **argv)
 		setenv(GIT_PROTOCOL_ENVIRONMENT, proto_header, 0);
 
 	cmd->imp(&hdr, cmd_arg);
+	free(cmd_arg);
 	return 0;
 }