linux-user/elfload: test return value of getrlimit

linux-user/elfload: test return value of getrlimit

Should getrlimit() fail the value of dumpsize.rlimit_cur may not be
initialized. Avoid reading garbage data by checking the return value of
getrlimit.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
Message-Id: <20240120-qemu-user-dumpable-v3-1-6aa410c933f1@t-8ch.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>