Two corrections:

* When reconfiguring, make sure the config.cache file is blown away so that
  its (old) values don't short-circuit doing the tests. When a reconfigure
  is done, it should be done from scratch, without the cache.
* For dist-check, don't pass --with-llvmgccdir any more because configure
  doesn't have this option any more.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19126 91177308-0d34-0410-b5e6-96231b3b80d8