[4/n] BumpPool: fix available size calc

Bug: 177241396
Change-Id: I7ed8958985bb2e2ca4e16d727c3b013a8f550fe4
1 file changed
tree: f5819d713d641ca3981b3ac46ad1dd0aa960cf5f
  1. base/
  2. host-common/
  3. snapshot/