pgsql: psql code cleanup: - refactor a bunch of code to call a separate

Log Message:
-----------
psql code cleanup:

- refactor a bunch of code to call a separate function print_msg() which
checks whether "silent mode" is enabled before printing an error
message.

- rename "silence_mode" to "silent_mode", which IMHO makes more sense

- make the error messages we emit in "waiting" mode more consistent; I
believe this fixes a recent error message regression

Modified Files:
--------------
    pgsql/src/bin/pg_ctl:
        pg_ctl.c (r1.35 -> r1.36)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_ctl/pg_ctl.c.diff?r1=1.35&r2=1.36)