Add x64 build for appveyor.
Add x64 build for appveyor.

xpol/lua-rapidjson,xpol/lua-rapidjson,ignacio/lua-rapidjson,ycsoft/lua-rapidjson,ignacio/lua-rapidjson,ignacio/lua-rapidjson,tvbeat/lua-rapidjson,ycsoft/lua-rapidjson,ycsoft/lua-rapidjson,ignacio/lua-rapidjson,ycsoft/lua-rapidjson,tvbeat/lua-rapidjson