pgsql: Revert previous patch to put the shared memory segment on win32

Log Message:
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Revert previous patch to put the shared memory segment on win32
in the Global\ namespace, because it caused permission errors on
a lot of platforms.

We need to come up with something better for 8.4, but for now
revert to the pre-8.3.4 behaviour.

Tags:
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REL8_3_STABLE

Modified Files:
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pgsql/src/backend/port:
win32_shmem.c (r1.4.2.1 -> r1.4.2.2)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win32_shmem.c?r1=1.4.2.1&r2=1.4.2.2)