rgw_rados.h: RGWRegion: initialize cct and store with NULL

CID 1054869 (#1 of 1): Uninitialized pointer field (UNINIT_CTOR)
 4. uninit_member: Non-static class member "store" is not initialized
    in this constructor nor in any functions that it calls
 2. uninit_member: Non-static class member "cct" is not initialized
    in this constructor nor in any functions that it calls.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>