chore(callgrind): log new_fn_node creation with fn and obj name

Fires once per fn_node, before any call edge is built. Lets us see the
exact obj path string Callgrind stores for a function (e.g. PyEval) so
we can compare it against the obj_skip list independently of any
strcmp result.

Author: not-matthias

callgrind/fn.c

@@ -511,6 +511,10 @@ fn_node* new_fn_node(const HChar *fnname,
     fn->toggle_collect = False;
     fn->skip         = False;
     fn->obj_skip_checked = False;
+
+    VG_(message)(Vg_UserMsg, "new_fn_node: fn='%s' obj='%s'\n",
+                 fn->name,
+                 (file && file->obj && file->obj->name) ? file->obj->name : "(null)");
     fn->pop_on_jump  = CLG_(clo).pop_on_jump;
     fn->is_malloc    = False;
     fn->is_realloc   = False;