perf data: Increase RLIMIT_NOFILE limit when open too many files in perf_data__create_dir()

If using parallel threads to collect data, perf record needs at least 6 fds
per CPU. (one for sys_perf_event_open, four for pipe msg and ack of the
pipe, see record__thread_data_open_pipes(), and one for open perf.data.XXX)
For an environment with more than 100 cores, if perf record uses both
`-a` and `--threads` options, it is easy to exceed the upper limit of the
file descriptor number, when we run out of them try to increase the limits.

Before:
  $ ulimit -n
  1024
  $ lscpu | grep 'On-line CPU(s)'
  On-line CPU(s) list:                0-159
  $ perf record --threads -a sleep 1
  Failed to create data directory: Too many open files

After:
  $ ulimit -n
  1024
  $ lscpu | grep 'On-line CPU(s)'
  On-line CPU(s) list:                0-159
  $ perf record --threads -a sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.394 MB perf.data (1576 samples) ]

Signed-off-by: Yang Jihong <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>

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