bug#10918: srfi-4 functions return wrong length for bytevectors

[Tobias Brandt]

Applying any of the f/u/s*vector-length functions to
a bytevector returns the wrong size. Specifically they
multiply (instead of dividing) the size of the bytevector
by the size of one element.

scheme@(guile-user)> (use-modules (rnrs bytevectors))
scheme@(guile-user)> (define bv (make-bytevector 4))
scheme@(guile-user)> (bytevector-length bv)
$1 = 4
scheme@(guile-user)> (f32vector-length bv)
$2 = 16

I believe $2 should be 1, or am I interpreting the
documentation wrong?