perf annotate: Remove requirement of passing a symbol name

perf annotate: Remove requirement of passing a symbol name

If the user doesn't pass a symbol name to annotate, it will
annotate all the symbols that have hits, in order, just like
'perf report -s comm,dso,symbol'.

This is a natural followup patch to the one that uses
output_hists to find the symbols with hits.

The common case is to annotate the first few entries at the top
of a perf report, so lets type less characters.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1256058509-19678-1-git-send-email-acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>