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

Commit f231af78 ("perf test shell: Fix check open filename arg using
'perf trace' on s390x") added an exception for s390x to use openat()
instead of open() in the test that intercepts a open syscall to look for
the filename argument as obtained by the vfs_getname 'perf probe' it
puts in place at the getname_flags kernel function.

Its not just s390x that uses openat() instead of open(), so use 'perf
list' to look for the syscall:sys_enter_open(at)? present in the system
being tested instead of checking if the system is s390x.

In fact Namhyung pointed out that glibc 2.26 changed this behaviour, as
described in https://lwn.net/Articles/738694/

, so systems where glibc is
>= 2.26 will need this patch for this test to work, which already took
place in some distros for architectures such as s390x, while Fedora 26
x86_64 is at glibc 2.25, i.e. still uses open().

Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Link: https://lkml.kernel.org/r/ab23fe42-1080-a46b-503e-744e097f414f@linux.vnet.ibm.com
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
LPU-Reference: 1275675985.12835754.1513095723265.JavaMail.zimbra@redhat.com
Link: https://lkml.kernel.org/n/tip-j2wbz9av1rw3thr3t0g4dtuk@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>