virtual/{{c,}blas,lapack{,e}}: replaced by counterparts in ::gentoo.

  sci-libs/{{c,}blas,lapack{,e}}-reference: Remove.

  Remove BLAS/LAPACK migration scripts.
  Remove outdated documentation on BLAS/LAPACK.
  Update README.md to point to the new framework in ::gentoo.

Reference: https://wiki.gentoo.org/wiki/Blas-lapack-switch

Closes: https://github.com/gentoo/sci/issues/805
Closes: https://github.com/gentoo/sci/issues/926
Closes: https://github.com/gentoo/sci/issues/734
Closes: https://github.com/gentoo/sci/issues/897
Closes: https://github.com/gentoo/sci/issues/925

Package-Manager: Portage-2.3.69, Repoman-2.3.12
Signed-off-by: Benda Xu <[email protected]>

Author: heroxbd

README.md

@@ -14,16 +14,11 @@ wget https://gitweb.gentoo.org/proj/sci.git/plain/metadata/science.conf -O /etc/
 
 To start using the overlay you now only need to get the ebuilds, via `emerge --sync`.
 
-### BLAS and LAPACK Migration
+### BLAS and LAPACK
 
-There is a long-standing BLAS and LAPACK stack incompatibility between the Science Overlay and the Base Gentoo Overlay.
-A fix [is being considered](https://github.com/gentoo/sci/issues/805), bit is still not scheduled for implementation.
-In the mean time, the most automated and up-to-date solution (building on [the original one](https://wiki.gentoo.org/wiki/User_talk:Houseofsuns)) is to run (as root, and after having installed the overlay):
-
-```
-cd ${EPREFIX}/var/lib/overlays/science/scripts
-./lapack-migration.sh
-```
+[The BLAS and LAPACK switching framework](https://wiki.gentoo.org/wiki/Blas-lapack-switch)
+in ::gentoo has been implemented. The Science overlay will no longer
+carry blas and lapack ebuilds.
 
 ### Uninstall