Fix -ftime-report for C++ lookup

[Diego Novillo]

Found this while running -ftime-report on a largish C++ source file.
We need to start TV_NAME_LOOKUP conditionally inside poplevel()
because it may be called from another lookup routine that already has
TV_NAME_LOOKUP going.

Tested on x86_64.  Committed to trunk.

2012-08-20  Diego Novillo  <dnovi...@google.com>

        * decl.c (poplevel): Start TV_NAME_LOOKUP conditionally.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 5908996..0dad597 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -552,7 +552,7 @@ poplevel (int keep, int reverse, int functionbody)
   unsigned ix;
   cp_label_binding *label_bind;

-  timevar_start (TV_NAME_LOOKUP);
+  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  restart:

   block = NULL_TREE;
@@ -818,7 +818,7 @@ poplevel (int keep, int reverse, int functionbody)
   if (kind == sk_cleanup)
     goto restart;

-  timevar_stop (TV_NAME_LOOKUP);
+  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
   return block;
 }