[leaks] The PDFileEntry nodes in the FilesMade FoldingSet contain
a std::vector that allocates on the heap. As a consequence, we have to
run all of their destructors when tearing down the set, not just
deallocate the memory blobs.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@207902 91177308-0d34-0410-b5e6-96231b3b80d8