perf tests: Switch from open to openat

Multiple perf tests fail on arm64 due to missing open syscall:

 2: detect open syscall event                              : FAILED!

open(2) is a legacy syscall, replaced with openat(2) since 2.6.16.  Thus
new architectures in kernel, such as arm64, don't implement these legacy
syscalls.

The patch replaces all sys_enter_open events with sys_enter_openat,
renames the related tests and test output to avoid confusion.

Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1429192375-13706-2-git-send-email-riku.voipio@linaro.org


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