pgsql: Remove unnecessary "head" arguments from some dlist/slist functi

Remove unnecessary "head" arguments from some dlist/slist functions.

dlist_delete, dlist_insert_after, dlist_insert_before, slist_insert_after
do not need access to the list header, and indeed insisting on that negates
one of the main advantages of a doubly-linked list.

In consequence, revert addition of "cache_bucket" field to CatCTup.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/dc5aeca168629183e64087b1147d3c2645e49ddc

Modified Files
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src/backend/postmaster/autovacuum.c | 17 +++++++-----
src/backend/postmaster/postmaster.c | 4 +-
src/backend/utils/cache/catcache.c | 8 ++----
src/include/lib/ilist.h | 45 +++++++++-------------------------
src/include/utils/catcache.h | 1 -
5 files changed, 27 insertions(+), 48 deletions(-)