use SHLIB_EXT for all GMP easyconfigs

Signed-off-by: Fotis Georgatos <fotis.georgatos@uni.lu>
use SHLIB_EXT for all MPFR easyconfigs

Signed-off-by: Fotis Georgatos <fotis.georgatos@uni.lu>
Merge pull request #1090 from fgeorgatos/bugfix_GMP_MFPR_etc

Bugfix GMP MPFR etc