redundant licenses

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

pkgsrc/licenses/expatobjc-license should be removed and any
reference of it should use the pkgsrc/licenses/mit LICENSE instead.

pkgsrc/licenses/amap-license and pkgsrc/licenses/hydra-license are the 
same license, but names changed.

pkgsrc/licenses/apache-1.1 and pkgsrc/licenses/radiance-license are the 
same license, but names changed.

pkgsrc/licenses/cpl-1.0 and pkgsrc/licenses/postfix-license are near the 
same. (But maybe keep both of these.