[RFA]: Fix perf pb in gas/decode_local_label_name

[Nick Clifton]

Hi Stephane,

> 2001-02-22  Stephane Carrez  <Stephane.Carrez@worldnet.fr>
> 
> 	* symbols.c (decode_local_label_name): Initialize message_format
> 	only when an error is reported (perf pb due to I18N).

Approved for trunk.

Cheers
        Nick