[CGDebugInfo] Simplify EmitFunctionDecl parameters, NFC

Replace a `llvm::Function *` parameter with a bool, which seems harder
to set to the wrong value by accident.

Differential Revision: https://reviews.llvm.org/D64540

llvm-svn: 365809
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 7edbea8..ca713fc 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -408,10 +408,11 @@
   /// End an inlined function scope.
   void EmitInlineFunctionEnd(CGBuilderTy &Builder);
 
-  /// Emit debug info for a function declaration.
-  /// \p Fn is set only when a declaration for a debug call site gets created.
-  void EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
-                        QualType FnType, llvm::Function *Fn = nullptr);
+  /// Emit debug info for a function declaration. Set \p IsDeclForCallSite if
+  /// a call site entry must reference the declaration.
+  llvm::DISubprogram *EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
+                                       QualType FnType,
+                                       bool IsDeclForCallSite = false);
 
   /// Emit debug info for an extern function being called.
   /// This is needed for call site debug info.