pgsql: Treat exit code 128 (ERROR_WAIT_NO_CHILDREN) as non-fatal on Win

Treat exit code 128 (ERROR_WAIT_NO_CHILDREN) as non-fatal on Win32,
since it can happen when a process fails to start when the system
is under high load.

Per several bug reports and many peoples investigation.

Back-patch to 8.2, since testing shows no issues even though the
"deadman-switch" does not exist  in this version.

Branch
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REL8_3_STABLE

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=26b01668cbd8bd1ad72b8eaca39f74323e5fbdc0

Modified Files
--------------
src/backend/postmaster/postmaster.c |   13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)