Provide names for template and function parameters in forward declarations.  The purpose is to aid automated documentation tools.

llvm-svn: 133008
diff --git a/libcxx/include/regex b/libcxx/include/regex
index b8b4a28..c4c58a4 100644
--- a/libcxx/include/regex
+++ b/libcxx/include/regex
@@ -2410,7 +2410,7 @@
     }
 }
 
-template <class, class> class __lookahead;
+template <class _CharT, class _Traits> class __lookahead;
 
 template <class _CharT, class _Traits = regex_traits<_CharT> >
 class _LIBCPP_VISIBLE basic_regex