Options, Meta APIs: Avoid a race condition causing the first of two subsequent...

Options, Meta APIs: Avoid a race condition causing the first of two subsequent requests updating different options at the same time to lose changes.

Every time an autoloaded option is updated or deleted, the `alloptions` cache is similarly updated. Due to the race condition, on any autoloaded option being updated, every other autoloaded option had its value set to the value at load time, causing a mismatch between the data in the persistent cache and the database.

This change introduces a `$force_cache` parameter for `wp_load_alloptions()` to force an update of the local `alloptions` cache from the persistent cache when an option is added, updated, or deleted, to minimize the chance of affecting other options.

Props fabifott, rmccue, tollmanz, johnjamesjacoby, spacedmonkey, dd32, jipmoors, tellyworth, jeremyclarke, joehoyle, boonebgorges, danielbachhuber, flixos90, jeichorn, mihdan, Grzegorz.Janoszka, SergeyBiryukov.
See #31245.
Built from https://develop.svn.wordpress.org/trunk@46753


git-svn-id: https://core.svn.wordpress.org/trunk@46553 1a063a9b-81f0-0310-95a4-ce76da25c4cd