pgsql: Clean up a couple of box gist helper functions.

Clean up a couple of box gist helper functions.

The original idea of this patch was to make box picksplit run faster, by
eliminating unnecessary palloc() overhead, but that was obsoleted by the new
double-sorting split algorithm that doesn't call these functions so heavily
anymore. Nevertheless, the code looks better this way.

Original patch by me, reviewed and tidied up after the double-sorting patch
by Kevin Grittner.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/d50e1251946a6e59092f0a84fc903532eb599a4f

Modified Files
--------------
src/backend/access/gist/gistproc.c | 31 +++++++++++++------------------
1 files changed, 13 insertions(+), 18 deletions(-)