In dbDelta(), ensure we are not running CREATE TABLE queries for global tables we wish to not upgrade.

props fliespl.
fixes #22134.

Built from https://develop.svn.wordpress.org/trunk@26566


git-svn-id: http://core.svn.wordpress.org/trunk@26457 1a063a9b-81f0-0310-95a4-ce76da25c4cd