perf test code-reading: Fix perf_env setup for PTI entry trampolines

perf test code-reading: Fix perf_env setup for PTI entry trampolines

BugLink: https://bugs.launchpad.net/bugs/1836968
commit f6c66d73bb8192d357bb5fb8cd5826920f811d8c upstream.

The "Object code reading" test will not create maps for the PTI entry
trampolines unless the machine environment exists to show that the arch is
x86_64.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1528183800-21577-1-git-send-email-adrian.hunter@intel.com
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>