perf test record+probe_libc_inet_pton: Ask 'nm' for dynamic symbols

Adrian reported that this test fails in his system where:

  probe libc's inet_pton & backtrace it with ping: FAILED!
  root@kbl04:~/git/linux-perf# nm -g /lib/x86_64-linux-gnu/libc-2.19.so | grep inet_pton
  nm: /lib/x86_64-linux-gnu/libc-2.19.so: no symbols

This fails on ubuntu systems, with Adrian's being kubuntu 14.04, I
tested with ubuntu 14.04.4 and 18.04, and there we need to use the
-D/--dynamic 'nm' option to have this test working. And it works as well
with that on fedora 27, so use it.

Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Sandipan Das <sandipan@linux.vnet.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-zlfnbauad3ljlmtjgo0v660u@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>