Objecter::calc_target(): init best_locality with 0

Init best_locality to fix:

osdc/Objecter.cc:1519:26: warning: variable 'best_locality' may be
 uninitialized when used here [-Wconditional-uninitialized]
              (locality >= 0 && best_locality >= 0 &&
                                ^~~~~~~~~~~~~
osdc/Objecter.cc:1511:19: note: initialize the variable 'best_locality'
 to silence this warning
        int best_locality;
                         ^
                          = 0

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
ObjectCacher::_wait_for_write(): init 'bool done'

Init 'bool done' with 'false' to fix:

osdc/Objecter.h:915:27: warning: implicit conversion los: variable 'done'
 may be uninitialized when used here [-Wconditional-uninitialized]
      while (!done)
              ^~~~
osdc/ObjectCacher.cc:1399:14: note: initialize the variable 'done' to
 silence this warning
    bool done;
             ^
              = false

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
rbd-fuse.c: init 'rbd' in open_rbd_image()

Init 'rbd' in open_rbd_image() with NULL and add a check for
'rbd' before dereference it to fix:

rbd_fuse/rbd-fuse.c:182:29: warning: variable 'rbd' may be uninitialized
 when used here [-Wconditional-uninitialized]
        int ret = rbd_open(ioctx, rbd->image_name, &(rbd->image), NULL);
                                  ^~~
rbd_fuse/rbd-fuse.c:151:27: note: initialize the variable 'rbd' to silence
 this warning
        struct rbd_openimage *rbd;
                                 ^
                                  = NULL

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
rbd.cc: init 'snap_protected' to fix -Wconditional-uninitialized

Init 'snap_protected' with false to fix:

rbd.cc:544:35: warning: variable 'snap_protected' may be uninitialized
 when used here [-Wconditional-uninitialized]
      f->dump_string("protected", snap_protected ? "true" : "false");
                                  ^~~~~~~~~~~~~~
rbd.cc:482:22: note: initialize the variable 'snap_protected' to silence
 this warning
  bool snap_protected;
                     ^
                      = false

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