MFH: r408791

Remove CONFIGURE_LOG

ffmpeg now uses config.log instead of previously config.err.
Setting CONFIGURE_LOG in port Makefile has become obsolete.
No change in resulting package, no PORTREVISION bump.

PR: 207136
Submitted by: mi@ALDAN.algebra.com
Reviewed by: riggs
Approved by: ports-secteam (feld)