perf symbols: Split the dsos list into kernel and user parts

We don't need to look at modules in dsos__findnew because the
kernel events come only with user DSOs. Also we need a way to
list just the module DSOs so that we can create multiple sets of
maps, now that we will support maps for the variables in a
symtab.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1259346563-12568-3-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>