[VecOps] Implement max_size method of RAdoptAllocator
[VecOps] Implement max_size method of RAdoptAllocator

despite being optional, this is required by gcc 4.8 and gcc 4.9

karies/root,root-mirror/root,karies/root,root-mirror/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,karies/root,root-mirror/root,olifre/root,olifre/root,karies/root,karies/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,karies/root,olifre/root,olifre/root,karies/root,karies/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,root-mirror/root