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/tools/clang-check/ClangCheck.cpp b/clang/tools/clang-check/ClangCheck.cpp
index dac11ff..e190c07 100644
--- a/clang/tools/clang-check/ClangCheck.cpp
+++ b/clang/tools/clang-check/ClangCheck.cpp
@@ -124,8 +124,7 @@
 /// \c FixItRewriter.
 class FixItAction : public clang::FixItAction {
 public:
-  bool BeginSourceFileAction(clang::CompilerInstance& CI,
-                             StringRef Filename) override {
+  bool BeginSourceFileAction(clang::CompilerInstance& CI) override {
     FixItOpts.reset(new FixItOptions);
     Rewriter.reset(new FixItRewriter(CI.getDiagnostics(), CI.getSourceManager(),
                                      CI.getLangOpts(), FixItOpts.get()));