title: File separator in windows makefile
body: <p>This may have been asked before but recently I came across a windows make file which had both type of file separators.
  E.g. - following two lines from that make file :</p>
  
  <pre><code>SRC = src/test.cpp
  @mkdir lib\$(HOST) &gt; NUL
  </code></pre>
  
  <p>from when does windows have started supporting both type of file separators ?</p>