pgsql: Add a small cache of locks owned by a resource owner in Resource

Add a small cache of locks owned by a resource owner in ResourceOwner.

Back-patch 9.3-era commit eeb6f37d89fc60c6449ca12ef9e91491069369cb, to
improve the older branches' ability to cope with pg_dump dumping a large
number of tables.

I back-patched into 9.2 and 9.1, but not 9.0 as it would have required a
significant amount of refactoring, thus negating the argument that this
is by-now-well-tested code.

Jeff Janes, reviewed by Amit Kapila and Heikki Linnakangas.

Branch
------
REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/0e933fdf9463857d4788e2e638affdde865855ce

Modified Files
--------------
src/backend/storage/lmgr/lock.c       |  152 ++++++++++++++++++++++-----------
src/backend/utils/resowner/resowner.c |   95 ++++++++++++++++++++-
src/include/storage/lock.h            |    4 +-
src/include/utils/resowner.h          |    5 ++
4 files changed, 204 insertions(+), 52 deletions(-)