www/pecl-yar: Update from 2.0.2 to 2.0.4

Changelog:
https://pecl.php.net/package/yar/2.0.3
https://pecl.php.net/package/yar/2.0.4

*While here:

• Switch to DISTVERSION
• Pet portlint
• Add LICENSE_FILE
• Remove PHP 7.2 from IGNORE_WITH_PHP (with this Update, this Port is PHP 7.2 ready)

PR: 225246
Submitted by: johnpupu@gmail.com (maintainer)
Approved by: mentors (implicit)