change the 'is directory' indicator to be a null-or-not
pointer that is passed down through the APIs, and make
FileSystemStatCache::get be the one that filters out
directory lookups that hit files.  This also paves the
way to have stat queries be able to return opened files.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@120060 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed