With installer.dll the installer did the decision whether to install or
upgrade the driver according to installer.dll version and hash stored in
registry by MSM.
With wintun.dll we need to know, which version of Wintun driver we are
packing in the resources to decide about driver upgrade. The most
accurate source of the driver version is the DriverVer directive in
[Version] section of the driver's .inf file.
Signed-off-by: Simon Rozman <simon@rozman.si>