Mainly for consistency with the old deployment method in Qt Creator,
androiddeployqt will uninstall any previously installed instances
of the application before installing it. This will remove any caches
or user data stored by the application. In many cases (most) it
would be more convenient to just overwrite the existing instance,
but keep all caches intact. This patch adds the --reinstall option,
symmetrical to --install. If enabled, the uninstall step will be
skipped.

[ChangeLog][androiddeployqt] Added option to install an APK without
uninstalling previous instances of same application.

Task-number: QTBUG-35845
Change-Id: I93bed4fefda6ed5295f333002a4958654b3f911c
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>