pgsql: Allow float8, int8, and related datatypes to be passed by value

Log Message:
-----------
Allow float8, int8, and related datatypes to be passed by value on machines
where Datum is 8 bytes wide. Since this will break old-style C functions
(those still using version 0 calling convention) that have arguments or
results of these types, provide a configure option to disable it and retain
the old pass-by-reference behavior. Likewise, provide a configure option
to disable the recently-committed float4 pass-by-value change.

Zoltan Boszormenyi, plus configurability stuff by me.

Modified Files:
--------------
pgsql:
configure (r1.589 -> r1.590)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure?r1=1.589&r2=1.590)
configure.in (r1.555 -> r1.556)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure.in?r1=1.555&r2=1.556)
pgsql/contrib/btree_gist:
btree_cash.c (r1.6 -> r1.7)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_cash.c?r1=1.6&r2=1.7)
btree_time.c (r1.13 -> r1.14)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_time.c?r1=1.13&r2=1.14)
btree_ts.c (r1.14 -> r1.15)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_ts.c?r1=1.14&r2=1.15)
btree_utils_num.c (r1.9 -> r1.10)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_utils_num.c?r1=1.9&r2=1.10)
pgsql/doc/src/sgml:
installation.sgml (r1.306 -> r1.307)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/installation.sgml?r1=1.306&r2=1.307)
pgsql/src/backend/access/transam:
xlog.c (r1.297 -> r1.298)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.297&r2=1.298)
pgsql/src/backend/bootstrap:
bootstrap.c (r1.241 -> r1.242)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/bootstrap/bootstrap.c?r1=1.241&r2=1.242)
pgsql/src/backend/catalog:
genbki.sh (r1.43 -> r1.44)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/genbki.sh?r1=1.43&r2=1.44)
pgsql/src/backend/commands:
analyze.c (r1.118 -> r1.119)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/analyze.c?r1=1.118&r2=1.119)
pgsql/src/backend/optimizer/plan:
planagg.c (r1.37 -> r1.38)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planagg.c?r1=1.37&r2=1.38)
pgsql/src/backend/parser:
parse_node.c (r1.99 -> r1.100)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_node.c?r1=1.99&r2=1.100)
pgsql/src/backend/utils/adt:
cash.c (r1.78 -> r1.79)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/cash.c?r1=1.78&r2=1.79)
float.c (r1.154 -> r1.155)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/float.c?r1=1.154&r2=1.155)
int8.c (r1.68 -> r1.69)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/int8.c?r1=1.68&r2=1.69)
numeric.c (r1.109 -> r1.110)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/numeric.c?r1=1.109&r2=1.110)
tsquery_gist.c (r1.6 -> r1.7)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/tsquery_gist.c?r1=1.6&r2=1.7)
pgsql/src/backend/utils/fmgr:
README (r1.11 -> r1.12)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/fmgr/README?r1=1.11&r2=1.12)
fmgr.c (r1.116 -> r1.117)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/fmgr/fmgr.c?r1=1.116&r2=1.117)
pgsql/src/backend/utils/init:
flatfiles.c (r1.32 -> r1.33)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/init/flatfiles.c?r1=1.32&r2=1.33)
pgsql/src/bin/pg_controldata:
pg_controldata.c (r1.38 -> r1.39)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_controldata/pg_controldata.c?r1=1.38&r2=1.39)
pgsql/src/bin/pg_resetxlog:
pg_resetxlog.c (r1.64 -> r1.65)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_resetxlog/pg_resetxlog.c?r1=1.64&r2=1.65)
pgsql/src/include:
c.h (r1.225 -> r1.226)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/c.h?r1=1.225&r2=1.226)
fmgr.h (r1.57 -> r1.58)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/fmgr.h?r1=1.57&r2=1.58)
pg_config.h.in (r1.129 -> r1.130)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/pg_config.h.in?r1=1.129&r2=1.130)
postgres.h (r1.90 -> r1.91)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/postgres.h?r1=1.90&r2=1.91)
pgsql/src/include/catalog:
catversion.h (r1.449 -> r1.450)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.449&r2=1.450)
pg_attribute.h (r1.136 -> r1.137)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_attribute.h?r1=1.136&r2=1.137)
pg_control.h (r1.40 -> r1.41)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_control.h?r1=1.40&r2=1.41)
pg_type.h (r1.194 -> r1.195)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_type.h?r1=1.194&r2=1.195)
pgsql/src/include/tsearch:
ts_utils.h (r1.13 -> r1.14)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/tsearch/ts_utils.h?r1=1.13&r2=1.14)
pgsql/src/include/utils:
cash.h (r1.24 -> r1.25)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/cash.h?r1=1.24&r2=1.25)
pgsql/src/test/regress/expected:
type_sanity.out (r1.32 -> r1.33)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/type_sanity.out?r1=1.32&r2=1.33)
pgsql/src/test/regress/sql:
type_sanity.sql (r1.32 -> r1.33)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/type_sanity.sql?r1=1.32&r2=1.33)
pgsql/src/tools/msvc:
Genbki.pm (r1.3 -> r1.4)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/tools/msvc/Genbki.pm?r1=1.3&r2=1.4)