Rename php-xdebug to pecl-xdebug

[pizzamig]

Summary

Adopt pecl build framework
Fix devel's Makefile subdir entry
Add a proper entry in MOVED
Update WWW lines in pkg-descr

Test Plan

Build on poudriere with default versions

[olivier]

And what about updating all ports depending of your renamed ports ? like devel/pear-PHP_CodeCoverage

[pizzamig]

• Rename any reference/depends of php-xdebug to pecl-xdebug

[franco_opnsense.org]

Seeing this after migration...

[31-Jan-2018 08:01:55 Etc/UTC] PHP Warning: Xdebug MUST be loaded as a Zend extension in Unknown on line 0