perf machine: Fix to destroy kernel maps when machine exits

Actually machine__exit forgot to call machine__destroy_kernel_maps.

This fixes some memory leaks on map as below.

Without this fix.
  ----
  ./perf probe vfs_read
  Added new event:
    probe:vfs_read       (on vfs_read)

  You can now use it in all perf tools, such as:

          perf record -e probe:vfs_read -aR sleep 1

  REFCNT: BUG: Unreclaimed objects found.
  REFCNT: Total 4 objects are not reclaimed.
     To see all backtraces, rerun with -v option
  ----
With this fix.
  ----
  ./perf probe vfs_read
  Added new event:
    probe:vfs_read       (on vfs_read)

  You can now use it in all perf tools, such as:

          perf record -e probe:vfs_read -aR sleep 1

  REFCNT: BUG: Unreclaimed objects found.
  REFCNT: Total 2 objects are not reclaimed.
     To see all backtraces, rerun with -v option
  ----

Signed-off-by: Masami Hiramatsu <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/util/machine.c

@@ -122,6 +122,7 @@ void machine__delete_threads(struct machine *machine)
 
 void machine__exit(struct machine *machine)
 {
+	machine__destroy_kernel_maps(machine);
 	map_groups__exit(&machine->kmaps);
 	dsos__exit(&machine->dsos);
 	machine__exit_vdso(machine);