PAE on i686 by default in TH

[Marcin Krol]

> * 4GB is more and more common on consumer grade machines (heck, my
> not-so-now custom made laptop has 4GB)

Yet with PAE single process still won't be able to allocate more than
~3.2 gigs of RAM. So if someone really want to use more than 4 gigs of
memory x86_64 is way better choice.

> * some x86_64 servers are forced to run in 32-bit mode due to
> proprietary software or some other requirements

I'd rather virtualize such systems on x86_64 hosts, but thats just me :)

> Proposed changes:
> 
> * Reverse the pae bcond

Why not just build pae kernels like I do in Titanium for i686? Does it
have to be "kernel" instead of "kernel-pae"?

M.