An obsolete comment of pg_stat_statements

Hello.

I noticed obsolete lines in the function comment of pgss_store().

* If queryId is 0 then this is a utility statement for which we couldn't
* compute a queryId during parse analysis, and we should compute a suitable
* queryId internally.

Previously the function actually calculates queryId using
pgss_hash_string when the given queryId is 0, but since 14 the
function simply rejects to work. We can just drop the paragraph. Or
we can emphasize the change of the behavior by describing the current
behavior for the value.

The attached patch is doing the latter.

* queryId is supposed to be a valid value, otherwise this function dosen't
* calucate it by its own as before then returns immediately.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center