perf cpu_map: Align cpu map synthesized events properly.

The size of the resulting cpu map can be smaller than a multiple of
sizeof(u64), resulting in SIGBUS on cpus like Sparc as the next event
will not be aligned properly.

Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Fixes: 6c872901 ("perf cpu_map: Add cpu_map event synthesize function")
Link: http://lkml.kernel.org/r/20181011.224655.716771175766946817.davem@davemloft.net


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