perf test shell: Add uprobes + backtrace ping test

perf test shell: Add uprobes + backtrace ping test

Installs a probe on libc's inet_pton function, that will use uprobes,
then use 'perf trace' on a ping to localhost asking for just one packet
with the a backtrace 3 levels deep, check that it is what we expect.
This needs no debuginfo package, all is done using the libc ELF symtab
and the CFI info in the binaries.

Testing it:

  # perf test ping
  61: probe libc's inet_pton & backtrace it with ping       : Ok

In verbose mode:

  # perf test -v ping
  61: probe libc's inet_pton & backtrace it with ping       :
  --- start ---
  test child forked, pid 1007
  PING ::1(::1) 56 data bytes
  64 bytes from ::1: icmp_seq=1 ttl=64 time=0.058 ms
  --- ::1 ping statistics ---
  1 packets transmitted, 1 received, 0% packet loss, time 0ms
  rtt min/avg/max/mdev = 0.058/0.058/0.058/0.000 ms
  0.000 probe_libc:inet_pton:(7f75fce12a20))
  __GI___inet_pton (/usr/lib64/libc-2.24.so)
  getaddrinfo (/usr/lib64/libc-2.24.so)
  _init (/usr/bin/ping)
  test child finished with 0
  ---- end ----
  probe libc's inet_pton & backtrace it with ping: 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-idrntt4nbg15aafu8hjmv7sk@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>