pgsql-server: Adjust index locking rules as per my proposal of earlier

Log Message:
-----------
Adjust index locking rules as per my proposal of earlier today. You
now are supposed to take some kind of lock on an index whenever you
are going to access the index contents, rather than relying only on a
lock on the parent table.

Modified Files:
--------------
pgsql-server/src/backend/access/heap:
tuptoaster.c (r1.45 -> r1.46)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/heap/tuptoaster.c.diff?r1=1.45&r2=1.46)
pgsql-server/src/backend/access/index:
indexam.c (r1.74 -> r1.75)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/index/indexam.c.diff?r1=1.74&r2=1.75)
pgsql-server/src/backend/commands:
analyze.c (r1.76 -> r1.77)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/analyze.c.diff?r1=1.76&r2=1.77)
vacuum.c (r1.291 -> r1.292)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/vacuum.c.diff?r1=1.291&r2=1.292)
vacuumlazy.c (r1.45 -> r1.46)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/vacuumlazy.c.diff?r1=1.45&r2=1.46)
pgsql-server/src/backend/executor:
execUtils.c (r1.115 -> r1.116)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/executor/execUtils.c.diff?r1=1.115&r2=1.116)
pgsql-server/src/include/commands:
vacuum.h (r1.57 -> r1.58)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/commands/vacuum.h.diff?r1=1.57&r2=1.58)