Adding support to display sample misc field in form
of letter for each bit:

  # perf script -F +misc ...
   sched-messaging  1414 K     28690.636582:       4590 cycles ...
   sched-messaging  1407 U     28690.636600:     325620 cycles ...
   sched-messaging  1414 K     28690.636608:      19473 cycles ...
  misc field  __________/

The misc bits are assigned to following letters:

  PERF_RECORD_MISC_KERNEL        K
  PERF_RECORD_MISC_USER          U
  PERF_RECORD_MISC_HYPERVISOR    H
  PERF_RECORD_MISC_GUEST_KERNEL  G
  PERF_RECORD_MISC_GUEST_USER    g
  PERF_RECORD_MISC_MMAP_DATA*    M
  PERF_RECORD_MISC_COMM_EXEC     E
  PERF_RECORD_MISC_SWITCH_OUT    S
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180107160356.28203-9-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>