Fix ASTMerge tests that I broke in my previous commit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149759 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/lib/FrontendTool/ExecuteCompilerInvocation.cpp
index cfb185e..aef8474 100644
--- a/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -114,7 +114,7 @@
   // If there are any AST files to merge, create a frontend action
   // adaptor to perform the merge.
   if (!FEOpts.ASTMergeFiles.empty())
-    Act = new ASTMergeAction(Act, FEOpts.ASTMergeFiles[0]);
+    Act = new ASTMergeAction(Act, FEOpts.ASTMergeFiles);
 
   return Act;
 }