pgsql: Consistently use geteuid() not getuid(); there were a few places

Log Message:
-----------
Consistently use geteuid() not getuid(); there were a few places deviating
from our long-established standard.

Modified Files:
--------------
pgsql/contrib/mSQL-interface:
mpgsql.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/mSQL-interface/mpgsql.c.diff?r1=1.5&r2=1.6)
pgsql/src/backend/libpq:
be-secure.c (r1.55 -> r1.56)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/be-secure.c.diff?r1=1.55&r2=1.56)
pgsql/src/bin/initdb:
initdb.c (r1.72 -> r1.73)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/initdb/initdb.c.diff?r1=1.72&r2=1.73)
pgsql/src/bin/psql:
help.c (r1.99 -> r1.100)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/help.c.diff?r1=1.99&r2=1.100)
pgsql/src/bin/scripts:
common.c (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/scripts/common.c.diff?r1=1.15&r2=1.16)
pgsql/src/interfaces/libpq:
fe-secure.c (r1.65 -> r1.66)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/fe-secure.c.diff?r1=1.65&r2=1.66)