Forward-declare BalancedDelimiterTracker and then befriend it.

To tolerate GCC 4.0.1 used in Xcode 3.0.

Change-Id: Ia4f5987d3c44c22543ac2e2c2d96578a099700f2
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index f00002e..918bf11 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -410,12 +410,14 @@
     return PP.LookAhead(0);
   }
 
+  class BalancedDelimiterTracker;
+
   /// \brief Tracks information about the current nesting depth of 
   /// opening delimiters of each kind.
   class DelimiterTracker {
   private:
     friend class Parser;
-    friend class BalancedDelimiterTracker;
+    friend class Parser::BalancedDelimiterTracker;
 
     unsigned Paren, Brace, Square, Less, LLLess;
     unsigned& get(tok::TokenKind t) {