[CT-NG:patch 05/19] Force autoreconf for mpfr

In some exotic case the autoreconf step of mpfr is not executed (correctly)
leaving an incorrect version number for libtool in the configure script.

After extracting the sources files, force autoreconf to be executed.

Signed-off-by: Bart vdr. Meulen <bartvdrmeulen@gmail.com>

 This is NOT the official version of dialog.  This version has been

 significantly modified from the original.  It is for use by the Linux

 kernel configuration script.  Please do not bother Savio Lam with 

 questions about this program.