qrupdate.rb,slicot.rb: improved BLAS/LAPACK support.

I'd still like to see dotwrp, qrupdate, and slicot moved to homebrew-science per my last request. However, in the meanwhile, I've made two improvements.

First, on qrupdate.rb, I've added an OpenBLAS option, which is typical for a lot of the science libraries that depend on BLAS/LAPACK. Furthermore, I've eliminated the need for dotwrp by adding the "-ff2c" compilation flag when linking to vecLib. It's important to note that this does *not* prevent it from being linked to other code that does not use -ff2c, nor does it alter its C interface, because qrupdate.rb exports *only* subroutines. Eliminating a dependency in that case, therefore, makes sense, and is safe.

slicot.rb: originally I was going to add an OpenBLAS option here, but then it became clear that *no* BLAS/LAPACK specification is necessary, because it is building a static library. So I removed all mention of it.