added git submodule sync to vendor build in make
added git submodule sync to vendor build in make

tomgilder/OkHttpClient,scoodah/ModernHttpClient,tpurtell/ModernHttpClient,mattleibow/ModernHttpClient,leonardors/ModernHttpClient,paulcbetts/ModernHttpClient,tomgilder/OkHttpClient,djlewisxactware/ModernHttpClient,koltsov-ps/ModernHttpClient,xamarin/ModernHttpClient,kensykora/ModernHttpClient,nachocove/ModernHttpClient-demo,pacificIT/ModernHttpClient,nachocove/ModernHttpClient