qga-win: Fix a bug where qemu-ga service is stuck during stop operation

After triggering a freeze command without any following thaw command,
qemu-ga will not respond to stop operation. This behaviour is wanted on Linux
as there is no time limit for a freeze command and we want to prevent
quitting in the middle of freeze, on the other hand on Windows the time
limit for freeze is 10 seconds, so we should wait for the timeout, thaw
the file system and quit.

Signed-off-by: Sameeh Jubran <sameeh@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
