Improve support for non-portable mode

The attached patch adds a new configure option called --enable-tor-browser-data-in-home-dir and code to honor it.

This is effectively a special case of --enable-tor-browser-data-outside-app-dir. I developed this patch for the port of TBB to OpenBSD because we need to solve the problem of where the TorBrowser-Data directory goes. Under Linux it lives in the bundle. On Win/Mac there are canonical places for it to go. Under OpenBSD (and the other BSDs, at least), the logical place is the user's home directory, so I added this option and use it in my port's Makefile.

After discussion on #tor-dev I'm proposing this as a new feature to make it easier for other BSD/non-MacWinLin porting efforts.