Currently we can only remap a file by creating a MemoryBuffer and replacing the file contents with it.
Allow remapping a file by specifying another filename whose contents should be loaded if the original
file gets loaded. This allows to override files without having to create & load buffers in advance.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@127052 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/CacheTokens.cpp b/lib/Frontend/CacheTokens.cpp
index 5018224..06a1fd2 100644
--- a/lib/Frontend/CacheTokens.cpp
+++ b/lib/Frontend/CacheTokens.cpp
@@ -473,7 +473,7 @@
   for (SourceManager::fileinfo_iterator I = SM.fileinfo_begin(),
        E = SM.fileinfo_end(); I != E; ++I) {
     const SrcMgr::ContentCache &C = *I->second;
-    const FileEntry *FE = C.Entry;
+    const FileEntry *FE = C.OrigEntry;
 
     // FIXME: Handle files with non-absolute paths.
     if (llvm::sys::path::is_relative(FE->getName()))