perf test: Fix hist testcases when kptr_restrict is on

Currently if kptr_restrict is enabled, all hist tests failed with
segfaults.  This is because machine__create_kernel_maps() in
setup_fake_machine() failed in that situation, and it called
machine__delete() on the error path.  But outer callers again called
machines__exit() causing double free for the host machine.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1450062673-22312-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>