perf script: Make printing of dso a separate field option

perf script: Make printing of dso a separate field option

The 'sym' option displays both the function name and the DSO it comes
from. Split the display of the dso into a separate option.  This allows
display of the ip address and symbol without the dso, thus shortening
line lengths - and decluttering the output a bit.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1306528124-25861-3-git-send-email-dsahern@gmail.com
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>