Search for liblapack_atlas

[ktns]

On a debian/ubuntu box, clapack_xgetrf is in liblapack_atlas.so.

[translunar]

This is going to be a tricky one to merge, because we have to test it on a whole bunch of systems and can't just rely on Travis-CI. One thing you could do to make the process move a little faster is test it on a machine running Yosemite.

[ktns]

Sorry, I don't have immediate access to a MacOSX box, but I will test this patch on MacOSX soon. By the way, I think we can safely call have_library on a system without the library. What is your concern?

[translunar]

@ktns Have a look at the commit history for extconf.rb to get an idea for how complicated it has been to make this config work for all systems. =/

[v0dro]

@ktns could you please rebase again the current master and check if tests pass using the latest travis config? It should test for all systems.

[translunar]

Bump.