pgsql: Department of second thoughts: let's show the exact key during

Log Message:
-----------
Department of second thoughts: let's show the exact key during unique index
build failures, too. Refactor a bit more since that error message isn't
spelled the same.

Modified Files:
--------------
pgsql/src/backend/access/index:
genam.c (r1.75 -> r1.76)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/index/genam.c?r1=1.75&r2=1.76)
pgsql/src/backend/access/nbtree:
nbtinsert.c (r1.172 -> r1.173)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/nbtree/nbtinsert.c?r1=1.172&r2=1.173)
pgsql/src/backend/utils/sort:
tuplesort.c (r1.91 -> r1.92)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/sort/tuplesort.c?r1=1.91&r2=1.92)
pgsql/src/include/access:
genam.h (r1.80 -> r1.81)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/access/genam.h?r1=1.80&r2=1.81)
pgsql/src/test/regress/expected:
alter_table.out (r1.117 -> r1.118)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/alter_table.out?r1=1.117&r2=1.118)
create_index.out (r1.32 -> r1.33)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/create_index.out?r1=1.32&r2=1.33)