title: Does exist on Go something like macros in C++ like #ifdef so I can choose what to build based on flag?
body: <p>I need to build in go for linux and windows with different packages same file
  on windows I need to <code>import github.com/hashicorp/go-syslog</code> and on linux <code>import log/syslog</code></p>
  
  <p>and inside code in file I have to use <code>syslog.ALERT</code> or <code>gsyslog.ALERT</code> depending on os. Does exist on <code>Go</code> something like macros in <code>C++</code> like <code>#ifdef</code> so I can choose what to build based on flag ? How to achieve this without, same file to have different content for build based on OS ?</p>