perf lock contention: Show detail failure reason for BPF

It can fail to collect lock stat from BPF for various reasons.  For
example, I've got a report that sometimes time calculation seems wrong
in case of contended spinlocks.  I suspect the time delta went negative
for some reason.

Count them separately and show in the output like below:

$ sudo perf lock contention -abE5 sleep 10
 contended   total wait     max wait     avg wait         type   caller

        13    785.61 us     79.36 us     60.43 us     spinlock   remove_wait_queue+0x14
        10    469.02 us     87.51 us     46.90 us     spinlock   prepare_to_wait+0x27
         9    289.09 us     69.08 us     32.12 us     spinlock   finish_wait+0x36
       114    251.05 us      8.56 us      2.20 us     spinlock   try_to_wake_up+0x1f5
       132    188.63 us      5.01 us      1.43 us     spinlock   __wake_up_common_lock+0x62

=== output for debug ===

bad: 1, total: 279
bad rate: 0.36 %
histogram of failure reasons
       task: 1
      stack: 0
       time: 0

Signed-off-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Hao Luo <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

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