dev-lang/crystal: fix PATH path when bootstrapping

dev-lang/crystal: fix PATH path when bootstrapping

Before crystal-0.25.0 binary tarball directories did
not contain '-<N>' revisions:
    crystal-0.24.2-1-linux-x86_64 -> crystal-0.24.2
After crystal-0.25.0 they did:
    crystal-0.25.1-1-linux-x86_64 -> crystal-0.25.1-1

Ebuild missed the change and kept passing PATH without
'-<N>' revision.

This change resotres revision for crystal-0.26.0, 0.26.1
and adds sanity check to make sure expected directry
is in place. Should help catching the failure next time.

Reported-by: Myrddin Emrys
Bug: https://github.com/crystal-lang/crystal/issues/6650
Package-Manager: Portage-2.3.49, Repoman-2.3.10