perf test shell: Fix check open filename arg using 'perf trace' on s390x

perf test shell: Fix check open filename arg using 'perf trace' on s390x

This 'perf test' case fails on s390x. The 'touch' command on s390x uses
the 'openat' system call to open the file named on the command line:

[root@s35lp76 perf]# perf probe -l
  probe:vfs_getname    (on getname_flags:72@fs/namei.c with pathname)
[root@s35lp76 perf]# perf trace -e open touch /tmp/abc
     0.400 ( 0.015 ms): touch/27542 open(filename:
		/usr/lib/locale/locale-archive, flags: CLOEXEC) = 3
[root@s35lp76 perf]#

There is no 'open' system call for file '/tmp/abc'. Instead the 'openat'
system call is used:

[root@s35lp76 perf]# strace touch /tmp/abc
    execve("/usr/bin/touch", ["touch", "/tmp/abc"], 0x3ffd547ec98
			/* 30 vars */) = 0
    [...]
    openat(AT_FDCWD, "/tmp/abc", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666) = 3
    [...]

On s390x the 'egrep' command does not find a matching pattern and
returns an error.

Fix this for s390x create a platform dependent command line to enable
the 'perf probe' call to listen to the 'openat' system call and get the
expected output.

Signed-off-by: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
LPU-Reference: 20171114071847.2381-1-tmricht@linux.vnet.ibm.com
Link: http://lkml.kernel.org/n/tip-3qf38jk0prz54rhmhyu871my@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>