dev-utils/ccache: drop mpi support

MPI compilers are just wrappers around system compilers - if the
latter are supported by ccache mpi compilation will be supported
too.
sci-mathematics/alt-ergo: version bump

- version bump for a patch release 0.95.1;
- remove old and fix bug 479994 (wrong metadata for 0.95);
- cleanup metadata (there is no figure there).
drop stable keywords

Package-Manager: portage-2.2.1