QtIFW

Don't use 'lockmyApp' prefix for lock files

The 'lockmyApp' part of the lock file names looked like some generic
default value which just was not customized to fit the installer. Let's
use the Qt application name instead as returned by
QApplication::applicationName().

We maintain the strong random filename generation algorithm by sticking
to the proven constants which presumably are perfectly random since they
were generated by a fair die roll.

Change-Id: Ief18942ca4e967f7016e7c471a7b44e3b8ab8c95
Reviewed-by: Niels Weber <niels.weber@theqtcompany.com>
Reviewed-by: Katja Marttila <katja.marttila@theqtcompany.com>