encoding.c: add rb_enc_code_to_mbclen
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42077 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
encoding.c: add rb_enc_code_to_mbclen
mbclen from codepoint like as rb_enc_codelen() but 0 for invalid
char.
shortcut macro.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42077 b2dd03c8-39d4-4d8f-98ff-823fe69b080e