Log Message:
p5-Math-GMP: update to 2.15.

2.15  2017-06-25 Shlomif
    - Bump required perl version to 5.10.x.
        - There were test failures with 5.8.x and even 5.10.x is old enough.
        - http://www.cpantesters.org/cpan/report/256184b2-58bf-11e7-a074-e1beba07c9dd