[modules] Use a memory buffer directly as input for the module includes,
instead of messing with virtual files.

llvm-svn: 168062
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index cd15e212..6e82cd9 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -1796,6 +1796,10 @@
       MaybeAddSystemRootToFilename(F, F.OriginalSourceFileName);
       break;
 
+    case ORIGINAL_FILE_ID:
+      F.OriginalSourceFileID = FileID::get(Record[0]);
+      break;
+
     case ORIGINAL_PCH_DIR:
       F.OriginalDir.assign(BlobStart, BlobLen);
       break;