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When we lookup an address and don't find a map we should filter that
sample if the user specified a list of --dso entries to filter on, fix
it.

Before:

  $ perf script
             sleep 274800  2843.556162:          1 cycles:u:  ffffffffbb26bff4 [unknown] ([unknown])
             sleep 274800  2843.556168:          1 cycles:u:  ffffffffbb2b047d [unknown] ([unknown])
             sleep 274800  2843.556171:          1 cycles:u:  ffffffffbb2706b2 [unknown] ([unknown])
             sleep 274800  2843.556174:          6 cycles:u:  ffffffffbb2b0267 [unknown] ([unknown])
             sleep 274800  2843.556176:         59 cycles:u:  ffffffffbb2b03b1 [unknown] ([unknown])
             sleep 274800  2843.556180:        691 cycles:u:  ffffffffbb26bff4 [unknown] ([unknown])
             sleep 274800  2843.556189:       9160 cycles:u:      7fa9550eeaa3 __GI___tunables_init+0xf3 (/usr/lib64/ld-2.32.so)
             sleep 274800  2843.556312:      86937 cycles:u:      7fa9550e157b _dl_lookup_symbol_x+0x4b (/usr/lib64/ld-2.32.so)
  $

So we have some samples we somehow didn't find in a map for, if we now
do:

  $ perf report --stdio --dso /usr/lib64/ld-2.32.so
  # dso: /usr/lib64/ld-2.32.so
  #
  # Total Lost Samples: 0
  #
  # Samples: 8  of event 'cycles:u'
  # Event count (approx.): 96856
  #
  # Overhead  Command  Symbol
  # ........  .......  ........................
  #
      89.76%  sleep    [.] _dl_lookup_symbol_x
       9.46%  sleep    [.] __GI___tunables_init
       0.71%  sleep    [k] 0xffffffffbb26bff4
       0.06%  sleep    [k] 0xffffffffbb2b03b1
       0.01%  sleep    [k] 0xffffffffbb2b0267
       0.00%  sleep    [k] 0xffffffffbb2706b2
       0.00%  sleep    [k] 0xffffffffbb2b047d
  $

After this patch we get the right output with just entries for the DSOs
specified in --dso:

  $ perf report --stdio --dso /usr/lib64/ld-2.32.so
  # dso: /usr/lib64/ld-2.32.so
  #
  # Total Lost Samples: 0
  #
  # Samples: 8  of event 'cycles:u'
  # Event count (approx.): 96856
  #
  # Overhead  Command  Symbol
  # ........  .......  ........................
  #
      89.76%  sleep    [.] _dl_lookup_symbol_x
       9.46%  sleep    [.] __GI___tunables_init
  $
  #

Fixes: 96415e4d ("perf symbols: Avoid unnecessary symbol loading when dso list is specified")
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210128131209.GD775562@kernel.org

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>