Fix pgpool_setup to not confuse log output

Fix pgpool_setup to not confuse log output

Before it simply redirects the stdout and stderr of pgpool process to
a log file.  This could cause log contents being garbled or even
missed because of race condition caused by multiple process being
writing concurrently. I and Usama found this while investigating the
regression failure of 004.watchdog.

To fix this, pgpool_setup now generates startall script so that pgpool
now sends stdout/stderr to cat command and cat writes to the log file
(It seems the race condition does not occur when writing to a pipe).