main.c: Use the correct argv/argc

Before this, commandline handling would not work since
we were removing the program-name from the argv array.
With this fix, we will be able to use the standard
GApplication options.

$ gnome-maps --help-gapplication
$ gnome-maps --gapplication-service

etc.

https://bugzilla.gnome.org/show_bug.cgi?id=735215