Sharing 0-length ByteArray#s
Motivation
Currently each 0-length ByteArray# on the heap takes 16 bytes of heap space.
Yet, every copy is identical and could be shared just like we share constructors like Nothing
.
Proposal
Modify newByteArray# 0
and newPinnedByteArray# 0
so that repeated calls provide the same shared MutableByteArray#
.