Details:
- Separated bli_adjust_strides() into _alloc() and _attach() flavors so
that the latter can avoid a test performed by the former, in which the
rs and cs are overridden and set to zero if either matrix dimension is
zero. Actually, we also disable this overridding behavior, even for the
_alloc() case, since keeping the original strides (probably) does not
hurt anything. The original code has been kept commented-out, though,
in case an unintended consequence is later discovered.
- Fixed a typo in an error check for general stride cases where rs == cs.