tests/unit-test-client.c: apply "33ms > 20ms" test also to FreeBSD and OpenBSD

Signed-off-by: Jim Klimov <jimklimov+nut@gmail.com>

Author: jimklimov

tests/unit-test-client.c

@@ -739,10 +739,15 @@ int main(int argc, char *argv[])
         usleep(1000000);
         modbus_flush(ctx);
 
-#ifdef _WIN32
-        /* Timeout of 20ms between bytes, allow for 2*16+1
-         * Windows sleep seems to be at least 15ms always
-         */
+#if defined(_WIN32) || defined(__FreeBSD__) || defined(__OpenBSD__)
+         /* Timeout of 20ms between bytes, allow for 2*16+1
+          * Windows sleep seems to be at least 15ms always
+          * Windows sleep seems to be at least 15ms always.
+          * For some reason, FreeBSD 12 and OpenBSD 6.5 also
+          * tended to fail with 7ms variant as "gmake check"
+          * but pass in
+          * gmake -j 8 && ( ./tests/unit-test-server|cat & sleep 1 ; ./tests/unit-test-client|cat )
+          */
         TEST_TITLE("2/2 Adapted byte timeout (33ms > 20ms)");
         modbus_set_byte_timeout(ctx, 0, 33000);
         rc = modbus_read_registers(