perf tools: Complete support for dynamic strings

perf tools: Complete support for dynamic strings

Complete support for __str_loc type strings of ftrace events
which have dynamic offsets values set for each of them inside
their sammples.

Before:
        geany-5759  [000]     0.000000: lock_release: name
        geany-5759  [000]     0.000000: lock_release: name
        geany-5759  [000]     0.000000: lock_release: name
  kondemand/0-362   [000]     0.000000: lock_release: name
      pdflush-421   [000]     0.000000: lock_release: name

After:
        geany-5759  [000]     0.000000: lock_release: &u->lock
        geany-5759  [000]     0.000000: lock_release: key
        geany-5759  [000]     0.000000: lock_release: &group->notification_mutex
  kondemand/0-362   [000]     0.000000: lock_release: &rq->lock
      pdflush-421   [000]     0.000000: lock_release: &rq->lock

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1251693921-6579-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>