PATCH: CreateComments: use explicit indexing for ``values''

Hello,
I'm new to PostgreSQL and git, but having read through the wiki entries such as http://wiki.postgresql.org/wiki/Submitting_a_Patch, I think I have a patch worthy of submission.

It's a readability improvement in src/backend/commands/comment.c (CreateComments function), which changes the existing code from incrementing a variable for use as the array index, to use explicit ``values'' instead.

This has the following benefits

1) The structure of ``values'' is now clear at first glance.
2) ``i'' is then only used for 1 reason; the for loop

The patch is based on "master", and all existing tests pass.

Regards
Richard