perf test: "probe libc's inet_pton" fails on s390 due to missing inline

perf test "probe libc's inet_pton & backtrace it with ping" fails on
4.17.0rc3 on s/390. It turned out that function __inet_pton is reported
as inline:

  [root@s8360047 perf]# ./perf script -i /tmp/perf.data.111
  ping 12457 [000]  1584.478959: probe_libc:inet_pton: (3ffb5a347e8)
                    1347e8 __inet_pton (inlined)
                     f19d7 gaih_inet.constprop.5 (/usr/lib64/libc-2.24.so)
                     f4c3f __GI_getaddrinfo (inlined)
                      410b main (/usr/bin/ping)

Allow __inet_pton listed as inline.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180503065837.71043-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>