Simplify the code for calculating plugin API check timeout.

props leewillis77.
fixes #28600.
Built from https://develop.svn.wordpress.org/trunk@28805


git-svn-id: http://core.svn.wordpress.org/trunk@28614 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Introduce a binary-safe wrapper for strlen() and use it in seems_utf8(), utf8_uri_encode(), and wp_read_image_metadata().

Use binary-safe POMO_Reader::strlen() in MO::export_to_file_handle().

fixes #28162.
Built from https://develop.svn.wordpress.org/trunk@28806


git-svn-id: http://core.svn.wordpress.org/trunk@28615 1a063a9b-81f0-0310-95a4-ce76da25c4cd