query.php paging block clarity

[kawauso]

A few simple changes to the // Paging block in wp-includes/query.php

• $page is being checked with empty(), but is already passed through absint() which can only return an integer. Just using ! makes it a bit less confusing.

• $pgstrt = ''; is redundant as it's overwritten on the following line

• $limits = 'LIMIT ' . $pgstrt . $q['posts_per_page']; is repeated, so moved outside the if/else block for readability.

[ryan]

In [19724]:

Code cleanup in the paging block. Props kawauso. fixes #19773