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 <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Hendrik Brueckner <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Martin Schwidefsky <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Naveen N. Rao <[e-mail]>
Cc: Sandipan Das <[e-mail]>
Cc: Thomas Richter <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: https://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/shell/record+probe_libc_inet_pton.sh

···
 . $(dirname $0)/lib/probe.sh
 
 libc=$(grep -w libc /proc/self/maps | head -1 | sed -r 's/.*[[:space:]](\/.*)/\1/g')
-nm -g $libc 2>/dev/null | fgrep -q inet_pton || exit 254
+nm -Dg $libc 2>/dev/null | fgrep -q inet_pton || exit 254
 
 trace_libc_inet_pton_backtrace() {
 	idx=0