perf symbols: Use dso->long_name in dsos__find()

perf symbols: Use dso->long_name in dsos__find()

If not we end up duplicating the module DSOs because first we
insert them using the short name found in /proc/modules, then,
when processing synthesized MMAP events we add them again.

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: <1263519930-22803-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>