bug#19027: bytevector-fill! reject fill arguments larger than 127

[Mark H Weaver]

See the following session with Guile 2.0.11:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,use (rnrs bytevectors)
scheme@(guile-user)> (define bv (make-bytevector 8))
scheme@(guile-user)> (bytevector-fill! bv 255)
ERROR: In procedure bytevector-fill!:
ERROR: Value out of range -128 to 127: 255
--8<---------------cut here---------------end--------------->8---

I will fix this soon.

     Mark