the lowest version of perl available in ports is 5.8.9 which embed version
1.89 of Math::BigInt which is the same as the one available in
math/p5-Math-BigInt, so remove the useless dependency.
Keeping math/p5-Math-BigInt as it evolves alone
Bump port revision
It was created because of an article/challenge in "The Perl Review"
WWW: http://search.cpan.org/dist/Math-Base36/
PR: ports/126383
Submitted by: Yi-Hsuan Hsin <mhsin at mhsin.org>