crush: remove unused variables

crush: remove unused variables

[161/715] Building CXX object src/crush/CMakeFiles/crush_objs.dir/CrushTester.cc.o
ceph/src/crush/CrushTester.cc:478:7: warning: variable 'num_devices_active' set but not used [-Wunused-but-set-variable]
  int num_devices_active = 0;
      ^
1 warning generated.
[165/715] Building CXX object src/crush/CMakeFiles/crush_objs.dir/CrushWrapper.cc.o
ceph/src/crush/CrushWrapper.cc:1579:9: warning: variable 'local_changed' set but not used [-Wunused-but-set-variable]
    int local_changed = 0;
        ^

Signed-off-by: Casey Bodley <cbodley@redhat.com>