pgsql: Add a new builtin type, "uuid".

Log Message:
-----------
Add a new builtin type, "uuid". This implements a UUID type, similar to
that defined in RFC 4122. This patch includes the basic implementation,
plus regression tests. Documentation and perhaps some additional
functionality will come later. Catversion bumped.

Patch from Gevik Babakhani; review from Peter, Tom, and myself.

Modified Files:
--------------
pgsql/src/backend/utils/adt:
Makefile (r1.62 -> r1.63)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/Makefile.diff?r1=1.62&r2=1.63)
pgsql/src/include/catalog:
catversion.h (r1.376 -> r1.377)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.376&r2=1.377)
pg_amop.h (r1.77 -> r1.78)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_amop.h.diff?r1=1.77&r2=1.78)
pg_amproc.h (r1.62 -> r1.63)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_amproc.h.diff?r1=1.62&r2=1.63)
pg_cast.h (r1.28 -> r1.29)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_cast.h.diff?r1=1.28&r2=1.29)
pg_opclass.h (r1.73 -> r1.74)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_opclass.h.diff?r1=1.73&r2=1.74)
pg_operator.h (r1.148 -> r1.149)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_operator.h.diff?r1=1.148&r2=1.149)
pg_opfamily.h (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_opfamily.h.diff?r1=1.2&r2=1.3)
pg_proc.h (r1.440 -> r1.441)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.440&r2=1.441)
pg_type.h (r1.179 -> r1.180)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_type.h.diff?r1=1.179&r2=1.180)
pgsql/src/include/utils:
builtins.h (r1.286 -> r1.287)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h.diff?r1=1.286&r2=1.287)
pgsql/src/test/regress:
parallel_schedule (r1.37 -> r1.38)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/parallel_schedule.diff?r1=1.37&r2=1.38)
serial_schedule (r1.35 -> r1.36)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/serial_schedule.diff?r1=1.35&r2=1.36)

Added Files:
-----------
pgsql/src/backend/utils/adt:
uuid.c (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/uuid.c?rev=1.1&content-type=text/x-cvsweb-markup)
pgsql/src/include/utils:
uuid.h (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/uuid.h?rev=1.1&content-type=text/x-cvsweb-markup)
pgsql/src/test/regress/expected:
uuid.out (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/uuid.out?rev=1.1&content-type=text/x-cvsweb-markup)
pgsql/src/test/regress/sql:
uuid.sql (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/uuid.sql?rev=1.1&content-type=text/x-cvsweb-markup)