pgsql: Support only octal for psql PROMPT values, rather than the

Log Message:
-----------
Support only octal for psql PROMPT values, rather than the confusing
hex/decimal/octal. Documentation already updated.

BACKWARD COMPATIBLE CHANGE

Modified Files:
--------------
pgsql/src/bin/psql:
common.c (r1.97 -> r1.98)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/common.c.diff?r1=1.97&r2=1.98)
common.h (r1.42 -> r1.43)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/common.h.diff?r1=1.42&r2=1.43)
prompt.c (r1.38 -> r1.39)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/prompt.c.diff?r1=1.38&r2=1.39)