perf hist: Better displaying of unresolved DSOs and symbols

In the event that a DSO has not been identified, just print out [unknown]
instead of the instruction pointer as we previously were doing, which is pretty
meaningless for a shared object (at least to the users perspective).

The IP we print out is fairly meaningless in general anyway - it's just one
(the first) of the many addresses that were lumped together as unidentified,
and could span many shared objects and symbols. In reality if we see this
[unknown] output then the report -D output is going to be more useful anyway as
we can see all the different address that it represents.

If we are printing the symbols we are still going to see this IP in that column
anyway since they shouldn't resolve either.

This patch also changes the symbol address printouts so that they print out 0x
before the address, are left aligned, and changes the %L format string (which
relies on a glibc bug) to %ll.

Before:
    74.11%    :3259               4a6c  [k]     4a6c
After:
    74.11%    :3259  [unknown]          [k] 0x4a6c

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <1291603026-11785-2-git-send-email-imunsie@au1.ibm.com>
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>