Optional spkg for MPFRCX

[jpflori]

Include the MPFRCX library (http://mpfrcx.multiprecision.org) as an optional spkg.

Upstream tarball at:

• http://www.multiprecision.org/mpfrcx/download/mpfrcx-0.4.2.tar.gz

CC: @nexttime @nbruin

Component: packages: optional

Keywords: mpfrcx multiprecision.org complex real univariate polynomial ecc2011

Author: Jean-Pierre Flori

Branch: 71152b9

Reviewer: Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/11806

[zimmermann6]

Changed keywords from mpfrcx multiprecision.org complex real univariate polynomial to mpfrcx multiprecision.org complex real univariate polynomial ecc2011

[jpflori]

Description changed:

--- 
+++ 
@@ -1,3 +1,5 @@
 Include the MPFRCX library (http://mpfrcx.multiprecision.org) as an optional spkg.
 
-An spkg is available at http://www.infres.enst.fr/~flori/ecc2011/mpfrcx-0.3.1.spkg (or http://perso.telecom-paristech.fr/~flori/ecc2011/mpfrcx-0.3.1.spkg).
+
+Upstream tarball at:
+* http://www.multiprecision.org/mpfrcx/download/mpfrcx-0.4.2.tar.gz

[jpflori]

Commit: be4e538