util: Adjust qemu_guest_getrandom_nofail for Coverity

Explicitly ignore the return value of qemu_guest_getrandom.
Because we use error_fatal, all errors are already caught.

Fixes: CID 1401701
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190530173824.30699-1-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

util/guest-random.c

@@ -56,7 +56,7 @@ int qemu_guest_getrandom(void *buf, size_t len, Error **errp)
 
 void qemu_guest_getrandom_nofail(void *buf, size_t len)
 {
-    qemu_guest_getrandom(buf, len, &error_fatal);
+    (void)qemu_guest_getrandom(buf, len, &error_fatal);
 }
 
 uint64_t qemu_guest_random_seed_thread_part1(void)