Remove symbolt::is_procedure_local

It had a single user and wasn't actually a reliable indicator of whether a
symbol is procedure-local (in C/C++, a procedure-scoped variable may still have
static lifetime).

Author: tautschnig

src/analyses/constant_propagator.cpp

@@ -478,8 +478,9 @@ void constant_propagator_domaint::valuest::set_dirty_to_top(
 
     const symbolt &symbol=ns.lookup(id);
 
-    if((!symbol.is_procedure_local() || dirty(id)) &&
-       !symbol.type.get_bool(ID_C_constant))
+    if(
+      (symbol.is_static_lifetime || dirty(id)) &&
+      !symbol.type.get_bool(ID_C_constant))
     {
       it = replace_const.erase(it);
     }

src/util/symbol.h

@@ -97,11 +97,6 @@ class symbolt
     return !is_thread_local;
   }
 
-  bool is_procedure_local() const
-  {
-    return !is_static_lifetime;
-  }
-
   bool is_function() const
   {
     return !is_type && !is_macro && type.id()==ID_code;