title: Ccache doesn't work with gcc -M flag?
body: <p>I'm trying to use ccache to speed up my rebuilds and I noticed this in the log:</p>
  
  <pre><code>[2015-04-17T10:41:45.845545 27682] Compiler option -M is unsupported
  [2015-04-17T10:41:45.845584 27682] Failed; falling back to running the real compiler
  </code></pre>
  
  <p>In my experience you need something like the -M flag in order to have make or its equivalent trigger rebuilds correctly. It seems weird that ccache would be tripped up by an option that must be in almost every project's build. Am I missing something? Is there a more preferred option?</p>
  
  <p>This is w/ ccache-3.2.1.</p>
  
  <p>Edit: I tried with -MM as well, no luck.</p>