rmdir_if_possible should ignore EACCES

It was raising an exception, which stopped prune in its tracks when
something was installed root, eg. Fuse.

Library/Homebrew/pathname+yeast.rb

@@ -74,7 +74,7 @@ class Pathname
   def rmdir_if_possible
     rmdir
   rescue SystemCallError => e
-    raise unless e.errno == Errno::ENOTEMPTY::Errno
+    raise unless e.errno == Errno::ENOTEMPTY::Errno or e.errno == Errno::EACCES::Errno
   end
   
   def chmod_R perms