Adding mem2node object to allow the easy lookup of the node for the
physical address.

It has following interface:

  int  mem2node__init(struct mem2node *map, struct perf_env *env);
  void mem2node__exit(struct mem2node *map);
  int  mem2node__node(struct mem2node *map, u64 addr);

The mem2node__toolsinit initialize object from the perf data file
MEM_TOPOLOGY feature data. Following calls to mem2node__node will return
node number for given physical address. The mem2node__exit function
frees the object.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180309101442.9224-3-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>