PAE on i686 by default in TH

[Patryk Zawadzki]

Fedora 11 has declared they only supply an i686 kernel in PAE mode.
I'd like to propose the same for PLD Th.

Rationale:

* only very old hardware like first Pentium M chips does not support hardware
* 4GB is more and more common on consumer grade machines (heck, my
not-so-now custom made laptop has 4GB)
* some x86_64 servers are forced to run in 32-bit mode due to
proprietary software or some other requirements

Proposed changes:

* Reverse the pae bcond
* Ignore the bcond on ~i686 as it does not make sense there
* Drop the altkernel change caused by enabling the bcond (so we still
get the package named "kernel")

-- 
Patryk Zawadzki