Installer parameter msiparam is not working

[Stef74]

Whatever the value of -msiparam "X=Y", it is producing an error 'Unkown option "X=Y" ! Please refer to the command line help by specifying "/?" to get more information."

When I look into the installer code (https://www.virtualbox.org/browser/vbox/trunk/src/VBox/Installer/win/Stub/VBoxStub.cpp, aound line 406), I can see that the option index "i" is not increased at the same time as the local index "a". Therefore the global command line parser will check next i (ie "X=Y") right after -msiparams

-> increase "i" accordingly to "a" to go to the next parameter (see the same kind of behavior in "-path" treatment, 10 lines above)

This will also solve defect #7789

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.