* ext/openssl/ossl_bn.c (try_convert_to_bnptr): Extracted from
GetBNPtr(). This doesn't raise exception but returns NULL on error.
(GetBNPtr): Raise TypeError if conversion fails.
(ossl_bn_eq): Implement BN#==.
(ossl_bn_eql): #eql? should not raise TypeError even if the argument
is not compatible with BN.
(ossl_bn_hash): Implement BN#hash.
* ext/openssl/ossl_bn.c (Init_ossl_bn): Define #== and #hash.
* test/openssl/test_bn.rb: Test BN#eql?, #== and #hash
merge revision(s) 55047: [Backport #12441]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55906 b2dd03c8-39d4-4d8f-98ff-823fe69b080e