PX Uploader: Disable windowed mode

The windowed mode has been added for Windows targets originally. It gets very often incorrectly detected and slows down flashing considerably. This even applies to serial links. We are disabling it now in most circumstances.

Tools/px_uploader.py

@@ -344,8 +344,9 @@ class uploader(object):
         try:
             self.__getSync(False)
         except:
-            # if it fails we are on a real Serial Port
+            # if it fails we are on a real serial port - only leave this enabled on Windows
-            self.ackWindowedMode = True
+            if _platform.system() == 'Windows':
+                self.ackWindowedMode = True
 
         self.port.baudrate = self.baudrate_bootloader