title: gfortran doesn't work on Mac OS X 10.9
body: <p>I updated my Mac to OS X 10.9 GM, then I found that gfortran does not work. 
  When building any program, it shows:</p>
  
  <pre><code>ld: library not found for -lcrt1.10.5.o
  collect2: ld return 1
  </code></pre>
  
  <p>Does anyone know how I might solve this?</p>