androiddeployqt: Fix debug deployment on Windows

There is a bug in "adb push" which makes it fail when the input
directory ends with a slash on Windows. This made it impossible
to use the debug deployment method on Windows.

[ChangeLog][Android][androiddeployqt] Fixed debug deployment on
Windows.

Task-number: QTBUG-37028
Change-Id: I99bef5f2dc879cbd08dc0c7e6765395095b264cf
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>