CachePruning: fix typo, we accumulate file size here, not time

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266685
diff --git a/llvm/lib/Support/CachePruning.cpp b/llvm/lib/Support/CachePruning.cpp
index 0a3aef8..94a1668 100644
--- a/llvm/lib/Support/CachePruning.cpp
+++ b/llvm/lib/Support/CachePruning.cpp
@@ -76,7 +76,7 @@
           return;
         TotalSize += FileStatus.getSize();
         FileSizes.insert(
-            std::make_pair(FileAccessTime.seconds(), std::string(Path)));
+            std::make_pair(FileStatus.getSize(), std::string(Path)));
       };
 
   // Walk the entire directory cache, looking for unused files.