heap_profiler: support new gperftools header locations

The google/ headers location has been deprecated as of gperftools 2.0.
As of gperftools 2.2rc, the google/ headers will now give deprecation
warnings, and they will probably disappear in a future gperftools
update.

Signed-off-by: Ken Dreyer <kdreyer@redhat.com>
Merge pull request #3072 from ceph/wip-10231-gperftools-location

heap_profiler: support new gperftools header locations

gitbuilders are happy

Reviewed-by: Sage Weil <sage@redhat.com>