qapi-types: Drop unnedeed ._fwdefn

Previously, the generated code in qapi-types.c initialized all
enum lookup tables first, prior to any other definitions.  But
there are no topological sorting requirements that mandate this
layout, so we can drop the QAPISchemaGenTypeVisitor._fwdefn
field and just generate all definitions in visitation order.

The generated code shows some churn due to reordering, but it
is still fairly straightforward to follow (all the deletions
occur in one hunk, and all the deleted lines are re-inserted
in the same order later in the same files, just spread across
multiple insertion points).
Suggested-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1449033659-25497-6-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

scripts/qapi-types.py

@@ -168,21 +168,17 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
         self.decl = None
         self.defn = None
         self._fwdecl = None
-        self._fwdefn = None
         self._btin = None
 
     def visit_begin(self, schema):
         self.decl = ''
         self.defn = ''
         self._fwdecl = ''
-        self._fwdefn = ''
         self._btin = guardstart('QAPI_TYPES_BUILTIN')
 
     def visit_end(self):
         self.decl = self._fwdecl + self.decl
         self._fwdecl = None
-        self.defn = self._fwdefn + self.defn
-        self._fwdefn = None
         # To avoid header dependency hell, we always generate
         # declarations for built-in types in our header files and
         # simply guard them.  See also do_builtins (command line
@@ -209,7 +205,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
                 self.defn += gen_enum_lookup(name, values, prefix)
         else:
             self._fwdecl += gen_enum(name, values, prefix)
-            self._fwdefn += gen_enum_lookup(name, values, prefix)
+            self.defn += gen_enum_lookup(name, values, prefix)
 
     def visit_array_type(self, name, info, element_type):
         if isinstance(element_type, QAPISchemaBuiltinType):