[arch-releng] Support mobile broadband with wvdial

[Ray Rashif]

I refer to this:
http://mailman.archlinux.org/pipermail/arch-general/2010-June/014388.html

Other (desktop) distributions can skip wvdial on their installers
because they have (1) a desktop environment by default and as such (2)
some sort of GUI network management front-end that can handle most
types of connections, including mobile broadband [1]. However, we are
leaving out those users.

I had posted another link to configuring such connections with ppp
some months ago [2], but the fact of the matter is that it's all
pretty cumbersome. On the other hand, wvdial is a well-known method
for this and is easy to configure, aside from gathering ISP details
like APN and putting that in a file (etc/wvdial.conf).

Right now only the following people can install Arch Linux without
having to go through a number of hoops:

* with cable broadband
* with DSL broadband
* with wireless broadband

I believe we'd be pretty much 'complete' if we added:

* with mobile broadband

At least, in the 'broadband' category.

This effectively implies 2 packages from [extra]:

wvdial
wvstreams (dependency)

Since a package needn't be in [core] to be included in the image, I
say we should do this :)

[1] http://en.wikipedia.org/wiki/Mobile_broadband
[2] http://mailman.archlinux.org/pipermail/arch-general/2010-October/016727.html