pgsql: Clarify some error messages

Log Message:
-----------
Clarify some error messages

Modified Files:
--------------
    pgsql/src/backend/port/win32:
        security.c (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win32/security.c.diff?r1=1.5&r2=1.6)
        signal.c (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win32/signal.c.diff?r1=1.8&r2=1.9)
    pgsql/src/backend/postmaster:
        pgarch.c (r1.9 -> r1.10)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgarch.c.diff?r1=1.9&r2=1.10)
        postmaster.c (r1.436 -> r1.437)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/postmaster.c.diff?r1=1.436&r2=1.437)
        syslogger.c (r1.10 -> r1.11)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/syslogger.c.diff?r1=1.10&r2=1.11)