pgsql: Adjust permissions checking for ALTER OWNER commands: instead of

Log Message:
-----------
Adjust permissions checking for ALTER OWNER commands: instead of
requiring superuserness always, allow an owner to reassign ownership
to any role he is a member of, if that role would have the right to
create a similar object. These three requirements essentially state
that the would-be alterer has enough privilege to DROP the existing
object and then re-CREATE it as the new role; so we might as well
let him do it in one step. The ALTER TABLESPACE case is a bit
squirrely, but the whole concept of non-superuser tablespace owners
is pretty dubious anyway. Stephen Frost, code review by Tom Lane.

Modified Files:
--------------
pgsql/src/backend/commands:
aggregatecmds.c (r1.27 -> r1.28)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/aggregatecmds.c.diff?r1=1.27&r2=1.28)
conversioncmds.c (r1.20 -> r1.21)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/conversioncmds.c.diff?r1=1.20&r2=1.21)
dbcommands.c (r1.166 -> r1.167)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/dbcommands.c.diff?r1=1.166&r2=1.167)
functioncmds.c (r1.63 -> r1.64)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/functioncmds.c.diff?r1=1.63&r2=1.64)
opclasscmds.c (r1.34 -> r1.35)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/opclasscmds.c.diff?r1=1.34&r2=1.35)
operatorcmds.c (r1.23 -> r1.24)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/operatorcmds.c.diff?r1=1.23&r2=1.24)
schemacmds.c (r1.32 -> r1.33)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/schemacmds.c.diff?r1=1.32&r2=1.33)
tablecmds.c (r1.163 -> r1.164)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablecmds.c.diff?r1=1.163&r2=1.164)
tablespace.c (r1.25 -> r1.26)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablespace.c.diff?r1=1.25&r2=1.26)
typecmds.c (r1.75 -> r1.76)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/typecmds.c.diff?r1=1.75&r2=1.76)
pgsql/src/backend/utils/adt:
acl.c (r1.118 -> r1.119)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/acl.c.diff?r1=1.118&r2=1.119)
pgsql/src/include/utils:
acl.h (r1.81 -> r1.82)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/acl.h.diff?r1=1.81&r2=1.82)