tests: Make sure we get the requested number of bytes from /dev/urandom

src/tests.c

@@ -4913,7 +4913,7 @@ int main(int argc, char **argv) {
         }
     } else {
         FILE *frand = fopen("/dev/urandom", "r");
-        if ((frand == NULL) || !fread(&seed16, sizeof(seed16), 1, frand)) {
+        if ((frand == NULL) || fread(&seed16, sizeof(seed16), 1, frand) != sizeof(seed16)) {
             uint64_t t = time(NULL) * (uint64_t)1337;
             seed16[0] ^= t;
             seed16[1] ^= t >> 8;