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
------
REL8_2_STABLE

Details
-------
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=9c2ba6ad09aba37409c7535910e79425773fe568

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