Bump up the MaxDepth in the BalancedDelimiterTracker.

The Avida Project (http://avida.devosoft.org) exceeds the 256 limit.
rdar://11289131


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155737 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index 9d9a666..6404c9f 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -451,7 +451,7 @@
       }
     }
     
-    enum { MaxDepth = 256 };
+    enum { MaxDepth = 512 };
     
     bool diagnoseOverflow();
     bool diagnoseMissingClose();