Turn on MKPIE for ppc?

[Martin Husemann <martin%duskware.de@localhost>]

I wondered why we didn't have MKPIE=yes for powerpc architectures, so
I tested and

 a) it works
 b) it causes a 15% - 20% increased size for binaries (not shared libs,
    of course)

Do we want to enable it nevertheless?

Unfortunately packed relative relocs are not implemented for ppc apparently
in the current binutils version we have.

Martin