Always print out SourceManager stats with 'Stats' is true.  This revealed that PTH always pulls in the source pages with -fsyntax-only (investigating further).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@61996 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Driver/clang.cpp b/Driver/clang.cpp
index 268c26b..6b3507e 100644
--- a/Driver/clang.cpp
+++ b/Driver/clang.cpp
@@ -1409,8 +1409,7 @@
     PP.PrintStats();
     PP.getIdentifierTable().PrintStats();
     PP.getHeaderSearchInfo().PrintStats();
-    if (ClearSourceMgr)
-      PP.getSourceManager().PrintStats();
+    PP.getSourceManager().PrintStats();
     fprintf(stderr, "\n");
   }