[PATCH] Avoid forming references to an uninitialized memory in DroplessArena

[PATCH] Avoid forming references to an uninitialized memory in DroplessArena

Return a pointer from `alloc_raw` instead of a slice. There is no
practical use for slice as a return type and changing it to a pointer
avoids forming references to an uninitialized memory.

Gbp-Pq: Name u-1f0895162ba5a783d4d73d5c263552eaca9343b3.patch