zlib.c: zstream_expand_buffer_non_stream
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58524 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
zlib.c: zstream_expand_buffer_non_stream
zstream_expand_buffer_without_gvl() and replace duplicate code
in zstream_expand_buffer().
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58524 b2dd03c8-39d4-4d8f-98ff-823fe69b080e