Fixes for compiler warnings

Attached are patches to fix the following compiler warnings that I see when
using gcc 4.3.2.

MASTER warning:
tablecmds.c: In function 'DropErrorMsgWrongType':
tablecmds.c:601: warning: format not a string literal and no format
arguments

REL8_3_STABLE warnings:
utility.c: In function 'DropErrorMsgWrongType':
utility.c:129: warning: format not a string literal and no format arguments
trigger.c: In function 'ConvertTriggerToFK':
trigger.c:600: warning: format not a string literal and no format arguments
trigger.c:616: warning: format not a string literal and no format arguments
trigger.c:628: warning: format not a string literal and no format arguments
guc.c: In function 'set_config_option':
guc.c:4424: warning: format not a string literal and no format arguments
describe.c: In function 'describeOneTableDetails':
describe.c:1294: warning: format not a string literal and no format
arguments

Alan