unifdef MODULAR for powerpc

Hi,

There are a lot of ``#ifdef MODULAR'' in sys/arch/powerpc, in order to
provide ABI compatibility between oea/booke/ibm4xx kernels. However,
since 2011, we provide different kernel modules in /stand/modules for
the three architectures on evbppc. Therefore, I'd like to propose,

(1)  Unifdef MODULAR in sys/arch/powerpc.
(1') Expose {MIN,MAX}_PAGE_SIZE only for userland.
(2)  Provide kernel modules for three different archs also in /usr/tests.

Objections? And can you suggest any convenient method to realize (2)?

(a) How to build three different module binaries?
(b) How to select module binary in /usr/tests?

I will consider about it...

Thanks,
rin