[Rivet] GSL 1.8

[Andy Buckley]

Lars Sonnenschein wrote:
> Hello Andy
> gsl 1.8 is installed at CERN globally.
> Is this version fine or do we need a different (newer) one?
> (I personally installed version 1.9 for me, but ...)

Does it work? If so, then it's sufficient!

Has anyone else had any issues with the recent builds of Rivet which
require the GSL (GNU Scientific Library)? Note that you shouldn't need
the library headers - since it's a C library there's no issue with
inlining, so I just forward-declared everything that would have been in
the headers. Hence Rivet's GSL requirement should be satisfied by a
generic SL4 installation.

Andy