pgsql: Make use of qsort_arg in several places that were formerly using

Log Message:
-----------
Make use of qsort_arg in several places that were formerly using klugy
static variables. This avoids any risk of potential non-reentrancy,
and in particular offers a much cleaner workaround for the Intel compiler
bug that was affecting ginutil.c.

Modified Files:
--------------
pgsql/contrib/btree_gist:
btree_utils_var.c (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_utils_var.c.diff?r1=1.16&r2=1.17)
pgsql/contrib/tsearch2:
rank.c (r1.18 -> r1.19)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/rank.c.diff?r1=1.18&r2=1.19)
tsvector.c (r1.25 -> r1.26)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/tsvector.c.diff?r1=1.25&r2=1.26)
pgsql/src/backend/access/gin:
ginutil.c (r1.7 -> r1.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gin/ginutil.c.diff?r1=1.7&r2=1.8)
pgsql/src/backend/commands:
analyze.c (r1.99 -> r1.100)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/analyze.c.diff?r1=1.99&r2=1.100)
pgsql/src/include/access:
gin.h (r1.8 -> r1.9)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/gin.h.diff?r1=1.8&r2=1.9)