[Bug-gsl] Scalars are required to be double for all gsl_*_scale, gsl_*_add_constant regardless of element type

[Liam Healy]

The functions gsl_*_scale, gsl_*_add_constant seem to always require
the scalar which is added or multiplied is a double, regardless of the
vector or matrix element type.  For example, in
/usr/include/gsl/gsl_vector_int.h:

int gsl_vector_int_scale (gsl_vector_int * a, const double x);
int gsl_vector_int_add_constant (gsl_vector_int * a, const double x);

I checked a few of the .h files and they all seem this way; actual
tests on the different kinds of vectors and matrices has the effect
that the scalar is zero (i.e., for _add_constant the vector/matrix is
returned the same as supplied, for _const, the result is zero.).

(I am using GSL 1.11 from Debian Lenny).

Liam