Increase fixed waits in "pg_ctl start -w" from 5 seconds to 10.

Increase fixed waits in "pg_ctl start -w" from 5 seconds to 10.

In the 9.1 branch only, modify test_postmaster_connection() so that it
will wait up to 10 seconds, not 5, for the postmaster pid file to appear.
This is a much simpler and safer, if less complete, way of addressing
the buildfarm instability issues we hoped to solve with c869a7d5b.

Discussion: <20160618042812.5798.85609@wrigleys.postgresql.org>