* read.c (scm_lreadr): When user-defined hash procedure returns

* read.c (scm_lreadr): When user-defined hash procedure returns
SCM_UNSPECIFIED: Fall back to standard handling instead of raising
an exception.  (This prevents parsing of uniform vectors from
interfering with parsing of numbers.)

* arrays.scm (read:uniform-vector): Return *unspecified* instead
of raising an exception if hash extend character isn't followed by
the array list. (This prevents parsing of uniform vectors from
interfering with parsing of numbers.)