pgsql: Allow dynamic allocation of shared memory segments.

Allow dynamic allocation of shared memory segments.

Patch by myself and Amit Kapila. Design help from Noah Misch. Review
by Andres Freund.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/0ac5e5a7e152504c71ce2168acc9cef7fde7893c

Modified Files
--------------
configure | 177 ++++-
configure.in | 4 +-
doc/src/sgml/config.sgml | 26 +
src/backend/port/sysv_shmem.c | 26 +-
src/backend/storage/ipc/Makefile | 4 +-
src/backend/storage/ipc/dsm.c | 972 ++++++++++++++++++++++++
src/backend/storage/ipc/dsm_impl.c | 990 +++++++++++++++++++++++++
src/backend/storage/ipc/ipci.c | 5 +
src/backend/utils/misc/guc.c | 12 +
src/backend/utils/misc/postgresql.conf.sample | 7 +
src/backend/utils/resowner/resowner.c | 109 +++
src/bin/initdb/initdb.c | 1 +
src/include/pg_config.h.in | 3 +
src/include/portability/mem.h | 40 +
src/include/storage/dsm.h | 39 +
src/include/storage/dsm_impl.h | 75 ++
src/include/storage/lwlock.h | 1 +
src/include/utils/resowner_private.h | 8 +
18 files changed, 2470 insertions(+), 29 deletions(-)