qapi2texi: Include member type in generated documentation

The recent merge of docs/qmp-commands.txt and docs/qmp-events.txt into
the schema lost type information.  Fix this documentation regression.

Example change (qemu-qmp-ref.txt):

  -- Struct: InputKeyEvent

      Keyboard input event.

      Members:
-     'button'
+     'button: InputButton'
           Which button this event is for.
-     'down'
+     'down: boolean'
           True for key-down and false for key-up events.

      Since: 2.0

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1489582656-31133-26-git-send-email-armbru@redhat.com>

scripts/qapi2texi.py

@@ -135,8 +135,12 @@ def texi_enum_value(value):
 
 def texi_member(member):
     """Format a table of members item for an object type member"""
-    return '@item @code{%s}%s\n' % (
-        member.name, ' (optional)' if member.optional else '')
+    typ = member.type.doc_type()
+    return '@item @code{%s%s%s}%s\n' % (
+        member.name,
+        ': ' if typ else '',
+        typ if typ else '',
+        ' (optional)' if member.optional else '')
 
 
 def texi_members(doc, what, member_func):