Make the sys::Path::getFileStatus function more efficient by having it
return a pointer to the FileStatus structure rather than copy it. Adjust
uses of the function accordingly. Also, fix some memory issues in sys::Path.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35476 91177308-0d34-0410-b5e6-96231b3b80d8