pgsql-server: A few minor list-related cleanups: (1) Replace while loop

Log Message:
-----------
A few minor list-related cleanups:

(1) Replace while loop with the new forboth() construct in
parser/analyze.c

(2) Replace lcons() with lappend() in SearchCatCacheList(). Since these
now have the same performance, there is no reason to prefer lcons() in
this case, and using lappend() leads to cleaner code.

(3) Improve the name of the second parameter to for_each_cell()

Modified Files:
--------------
    pgsql-server/src/backend/parser:
        analyze.c (r1.311 -> r1.312)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/parser/analyze.c.diff?r1=1.311&r2=1.312)
    pgsql-server/src/backend/utils/cache:
        catcache.c (r1.116 -> r1.117)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/cache/catcache.c.diff?r1=1.116&r2=1.117)
    pgsql-server/src/include/nodes:
        pg_list.h (r1.49 -> r1.50)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/nodes/pg_list.h.diff?r1=1.49&r2=1.50)