解決更新 gcc 找不到 libgfortran.3.dylib (Octave,R)

最近在 mac 上更新了 gcc 6 後,不管是開 Octave 還是 R
都會出現以下的錯誤訊息

dyld: Library not loaded: /usr/local/lib/gcc/5/libgfortran.3.dylib
  Referenced from: /usr/local/Cellar/r/3.3.0/R.framework/Versions/3.2/Resources/lib/libR.dylib
  Reason: image not found
Trace/BPT trap: 5