pgsql: Marginal improvement in logging: include the function name when

Log Message:
-----------
Marginal improvement in logging: include the function name when logging
a fastpath function call.

Modified Files:
--------------
pgsql/src/backend/tcop:
fastpath.c (r1.93 -> r1.94)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/fastpath.c.diff?r1=1.93&r2=1.94)