Fix a bug with RingBuffer and read a u16 or u64 data.
Fix a bug with RingBuffer and read a u16 or u64 data.

For example, if we are at the end of the ring buffer and we try to
read a u64 data (so 8 bytes), we possibly lost the data and need to
go at the beginning of the ring buffer to the continue the reading
per byte.

Even if [idx] (used in [rb_*] function) is safe with [RingBuffer.sanitize],
[idx + n] (in [rb_u16] or [rb_u64]) is not safe. So we need to check and
Decompress is 2 times slower with that ...

oklm-wsh/Decompress,oklm-wsh/Decompress