oprofile 2.5.x backport to 2.4.20

[graydon h. <gr...@re...>]

hi,

attached is a backport of the oprofile kernel support from linux 2.5.x
to the public kernel.org version of linux 2.4.20. this is roughly the
patch we released with the recent phoebe beta, adjusted so it applies to
a stock kernel. it includes the dump interface, as well as p4 and
hyper-threading p4 (2 threads per CPU only) code. it does not include
hammer or ia64 support yet, and it might be slightly out of date wrt.
recent 2.5 bug fixes. we'll continue to try to get this 2.4 patch to
converge with the oprofile support in 2.5 and the older 2.4 features in
oprofile cvs, as much as possible.

I'm posting it in its current state to get some feedback, solicit some
help in porting features _forward_ to 2.5 (notably p4, hyper-threads)
and also possibly spark some discussion about future maintenance
directions. namely: where to keep this 2.4 patch (and versions of files
it has in common with 2.5) and whether to continue to support two kernel
interfaces. 

any thoughts?

-graydon