[pgpool-committers: 4288] pgpool: Fix exit signal handlers to not call ereport.

[Tatsuo Ishii]

Fix exit signal handlers to not call ereport.

There could be a race condition in the exit signal handlers. While
ereport is called in the handler, other interruption could call
ereport again. If ereport calls tz_convert which tries to acquire a
lock, it goes into a deadlock situation. In other word, tz_convert is
not reentrant and should not be used in signal handlers. So I removed
all ereport calls from exit signal handlers.

BTW pcp main calls ereport before the exception handler is
established. This could cause problem of course. So I fixed this
together. See [pgpool-hackers: 2545] for more details.

Branch
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V3_6_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=2ead26d767c7b1cdf826c952d7519ea70d67f3e7

Modified Files
--------------
src/main/pgpool_main.c  | 29 ++---------------------------
src/pcp_con/pcp_child.c | 24 ++++--------------------
2 files changed, 6 insertions(+), 47 deletions(-)