pgsql: pg_controldata needs #define FRONTEND, same as pg_resetxlog.

Log Message:
-----------
pg_controldata needs #define FRONTEND, same as pg_resetxlog.
Per buildfarm results from dawn_bat.

Modified Files:
--------------
pgsql/src/bin/pg_controldata:
pg_controldata.c (r1.47 -> r1.48)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_controldata/pg_controldata.c?r1=1.47&r2=1.48)