ENH: waf_tools: try to detect all blas/lapack libraries, and support 'generic' ones

It'd be nicer if the blas/lapack detection system tried all possible choices.

Moreover, it's probably useful to support 'generic' blas/lapack names as a last option. For instance on Ubuntu, the BLAS selection is done via libblas.so and liblapack.so symlinks in /usr/lib.