yum multilib_policy default for F9

[Bill Nottingham]

Matt Domsch (Matt_Domsch at dell.com) said: 
> What are the objections, besides timing (Alpha is finished, Beta is ~1
> month away) to switching the default from 'all' to 'best' for F9?

1) Software for the compat arch won't necessarily work out of the box.
   This includes third-party software for x86.
2) Tests need to be done to make sure on arches where the lower width
is primary (e.g., ppc, sparc) that the right thing happens, including
for things like debugging tools, libc, initramfs tools, etc. 

Bill