* bignum.c (rb_big_hash): make it public function to be available in
other source files, and remove documentation comment for Bignum#hash.
* bignum.c (Bignum#hash): remove its definition because it is unified
with Object#hash.
* include/ruby/intern.h (rb_big_hash): add a prototype declaration.
* hash.c (any_hash): treat Bignum values directly.
merge revision(s) 54168: [Backport #12391]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55633 b2dd03c8-39d4-4d8f-98ff-823fe69b080e