pgsql: Calculate # of semaphores correctly with --disable-spinlocks.

Calculate # of semaphores correctly with --disable-spinlocks.

The old formula didn't take into account that each WAL sender process needs
a spinlock. We had also already exceeded the fixed number of spinlocks
reserved for misc purposes (10). Bump that to 30.

Backpatch to 9.0, where WAL senders were introduced. If I counted correctly,
9.0 had exactly 10 predefined spinlocks, and 9.1 exceeded that, but bump the
limit in 9.0 too because 10 is uncomfortably close to the edge.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/9508754ed7e3b5688c97a26bbe15af7e11d7f06a

Modified Files
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src/backend/storage/lmgr/spin.c |   14 +++++++++++---
1 files changed, 11 insertions(+), 3 deletions(-)