submodule--helper, module_clone: catch fprintf failure

The return value of fprintf is unchecked, which may lead to
unreported errors. Use fprintf_or_die to report the error to the user.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/submodule--helper.c

@@ -229,8 +229,8 @@ static int module_clone(int argc, const char **argv, const char *prefix)
 	if (!submodule_dot_git)
 		die_errno(_("cannot open file '%s'"), sb.buf);
 
-	fprintf(submodule_dot_git, "gitdir: %s\n",
-		relative_path(sm_gitdir, path, &rel_path));
+	fprintf_or_die(submodule_dot_git, "gitdir: %s\n",
+		       relative_path(sm_gitdir, path, &rel_path));
 	if (fclose(submodule_dot_git))
 		die(_("could not close file %s"), sb.buf);
 	strbuf_reset(&sb);