pgsql: If test postmaster fails to start within 60 seconds, try to kill

Log Message:
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If test postmaster fails to start within 60 seconds, try to kill -9 it
so that it won't interfere with later trials.  Per recent buildfarm
experience.  Anyone know how to do this on Windows?

Modified Files:
--------------
    pgsql/src/test/regress:
        pg_regress.c (r1.19 -> r1.20)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/pg_regress.c.diff?r1=1.19&r2=1.20)