When reading file, add extra empty samples to ensure EOP detection.

Some test data files have too few "idle" samples at the end to ensure
end of packet is robustly detected. Decode an extra empty buffer to
ensure decoders are flushed.

src/rtl_433.c

@@ -1110,6 +1110,11 @@ int main(int argc, char **argv) {
             rtlsdr_callback(test_mode_buf, 131072, demod);
             i++;
         }
+
+        // Call a last time with cleared samples to ensure EOP detection
+        memset(test_mode_buf, 128, DEFAULT_BUF_LENGTH);     // 128 is 0 in unsigned data
+        rtlsdr_callback(test_mode_buf, 131072, demod);      // Why the magic value 131072?
+
         //Always classify a signal at the end of the file
         classify_signal();
         fprintf(stderr, "Test mode file issued %d packets\n", i);