perf test shell: Add test using vfs_getname + 'perf trace'

Uses the 'perf test shell' library to add probe:vfs_getname to the
system then use it with 'perf trace' using 'touch' to write to a temp
file, then checks that that was captured by the vfs_getname was used by
'perf trace', that already handles "probe:vfs_getname" if present, and
used in the "open" syscall "filename" argument beautifier.

Testing it:

  # perf test "trace + vfs_getname"
  61: Check open filename arg using perf trace + vfs_getname: Ok
  #

  # perf test -v "trace + vfs_getname"
  61: Check open filename arg using perf trace + vfs_getname:
  --- start ---
  test child forked, pid 30846
  Added new event:
    probe:vfs_getname    (on getname_flags:72 with pathname=result->name:string)

  You can now use it in all perf tools, such as:

  	perf record -e probe:vfs_getname -aR sleep 1

       2.237 ( 0.012 ms): touch/30855 open(filename: /tmp/temporary_file.kmoWQ, flags: CREAT|NOCTTY|NONBLOCK|WRONLY, mode: IRUGO|IWUGO) = 3
  test child finished with 0
  ---- end ----
  Check open filename arg using perf trace + vfs_getname: Ok
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-j02nobfvvn9c7yrphdsnbqx0@git.kernel.org


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