pgsql: Add \n to end of output for psql \s with no history file name.

Log Message:
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Add \n to end of output for psql \s with no history file name.

This prevents the next psql prompt from showing up on the end of the
last history line.

Modified Files:
--------------
pgsql/src/bin/psql:
command.c (r1.136 -> r1.137)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/command.c.diff?r1=1.136&r2=1.137)