pgsql: Change rather bizarre code ordering in get_id().

Log Message:
-----------
Change rather bizarre code ordering in get_id().  This isn't strictly
cosmetic --- I'm wondering if geteuid could have side effects on errno,
thus possibly resulting in a misleading error message after failure of
getpwuid.

Modified Files:
--------------
    pgsql/src/bin/initdb:
        initdb.c (r1.170 -> r1.171)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/initdb/initdb.c?r1=1.170&r2=1.171)