pgsql-server: Resurrect heap_deformtuple(), this time implemented as a

Log Message:
-----------
Resurrect heap_deformtuple(), this time implemented as a singly nested
loop over the fields instead of a loop around heap_getattr. This is
considerably faster (O(N) instead of O(N^2)) when there are nulls or
varlena fields, since those prevent use of attcacheoff. Replace loops
over heap_getattr with heap_deformtuple in situations where all or most
of the fields have to be fetched, such as printtup and tuptoaster.
Profiling done more than a year ago shows that this should be a nice
win for situations involving many-column tables.

Modified Files:
--------------
pgsql-server/src/backend/access/common:
heaptuple.c (r1.90 -> r1.91)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/common/heaptuple.c.diff?r1=1.90&r2=1.91)
printtup.c (r1.81 -> r1.82)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/common/printtup.c.diff?r1=1.81&r2=1.82)
pgsql-server/src/backend/access/heap:
tuptoaster.c (r1.41 -> r1.42)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/heap/tuptoaster.c.diff?r1=1.41&r2=1.42)
pgsql-server/src/backend/commands:
tablecmds.c (r1.109 -> r1.110)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/tablecmds.c.diff?r1=1.109&r2=1.110)
typecmds.c (r1.57 -> r1.58)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/typecmds.c.diff?r1=1.57&r2=1.58)
pgsql-server/src/backend/executor:
execJunk.c (r1.40 -> r1.41)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/executor/execJunk.c.diff?r1=1.40&r2=1.41)
spi.c (r1.115 -> r1.116)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/executor/spi.c.diff?r1=1.115&r2=1.116)
pgsql-server/src/include/access:
heapam.h (r1.89 -> r1.90)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/access/heapam.h.diff?r1=1.89&r2=1.90)