Log Message:
Update to 1.20 and unbreak

Upstream changes:
version 1.20; 2015-10-21

  * bugfix: avoid some C undefined behaviour from unsequenced side effects
    that in practice bit when using a newer gcc (4.9 rather than 4.7)
    with the parser token stack change in Perl 5.21.9

  * add doc note advising users to prefer the core aliasing facility on
    Perl 5.22

version 1.19; 2015-10-21

  * update for new stricture on op_last in Perl 5.21.2

  * update for the parser's PL_expect changes in Perl 5.21.4

  * update for op_private stricture in Perl 5.21.4

  * update for sub references directly in stash in Perl 5.21.4

  * update for IS_PADGV()'s limited visibility in Perl 5.21.4

  * update for increased specialness of OP_PUSHMARK in Perl 5.21.6

  * update for distinct PADNAMELIST type in Perl 5.21.7

  * update for multideref optimisation in Perl 5.21.7, by a disgusting
    hack that depends on a flaw in the optimisation (which may disappear
    in the future) and which disables the optimisation entirely

  * add MYMETA.json to .gitignore