[PATCH] uml: fix processor selection to exclude unsupported processors and features

Makes UML compile on any possible processor choice.  The two problems were:

*) x86 code, when 386 is selected, checks at runtime boot_cpuflags, which we do
   not have.

*) 3Dnow support for memcpy() et al. does not compile currently and fixing this
   is not trivial, so simply disable it; with this change, if one selects MK7
   UML compiles (while it did not).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>