`ruzstd` uninit and out-of-bounds memory reads

Affected versions of ruzstd miscalculate the length of the allocated and init section of its internal RingBuffer, leading to uninitialized or out-of-bounds reads in copy_bytes_overshooting of up to 15 bytes.

This may result in up to 15 bytes of memory contents being written into the decoded data when decompressing a crafted archive. This may occur multiple times per archive.