perf top: Auto adjust symbol and dso widths

We pre-calculate the symbol name length, then after we sort the
entries to print, calculate the biggest one and use that for the
symbol name width justification, then use the
dso->long_name->len to justificate the DSO name, deciding whether
using the short or long name depending on how much space we have
on the terminal.

IOW give as much info to the user as the terminal width allows.

Suggested-by: Ingo Molnar <mingo@elte.hu>
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: <1258479655-28662-2-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>