Remove 'Filename' parameter from BeginSourceFileAction.

No-one was using this, and it's not meaningful in general -- FrontendActions
can be run on inputs that don't have a corresponding source file. The current
frontend input can be obtained by asking the FrontendAction if any future
action actually needs it.

llvm-svn: 305045
diff --git a/clang/lib/Frontend/ASTMerge.cpp b/clang/lib/Frontend/ASTMerge.cpp
index 51064da..986f98a 100644
--- a/clang/lib/Frontend/ASTMerge.cpp
+++ b/clang/lib/Frontend/ASTMerge.cpp
@@ -21,14 +21,13 @@
   return AdaptedAction->CreateASTConsumer(CI, InFile);
 }
 
-bool ASTMergeAction::BeginSourceFileAction(CompilerInstance &CI,
-                                           StringRef Filename) {
+bool ASTMergeAction::BeginSourceFileAction(CompilerInstance &CI) {
   // FIXME: This is a hack. We need a better way to communicate the
   // AST file, compiler instance, and file name than member variables
   // of FrontendAction.
   AdaptedAction->setCurrentInput(getCurrentInput(), takeCurrentASTUnit());
   AdaptedAction->setCompilerInstance(&CI);
-  return AdaptedAction->BeginSourceFileAction(CI, Filename);
+  return AdaptedAction->BeginSourceFileAction(CI);
 }
 
 void ASTMergeAction::ExecuteAction() {