Log Message:
Update www/libproxy to 0.4.12.

pkgsrc changes:
 o Update MASTER_SITES and HOMEPAGE (libproxy migrated to GitHub)
 o Delete patches/patch-libproxy_modules_config__macosx.cpp, now present in the
   stable release.

Changes:
New in version 0.4.12
==============================
* Move development to github.com/libproxy/libproxy
* Fix fd leak in get_pac (Bug #185)
* Detect running MATE session (Bug #186, Part1).
* Fix linking of perl bindings to pthread (Bug #182)
* Correctly detect spidermonky (mozjs185) (Bug #188)
* Stop pxgsettings from segfaulting on exit (Bug #192)
* Fix test #10 (Bug #189)
* Fix build on Mac OS X (Bug #183)
* Add a generic KDE Config module (fix crashes of Qt5 based
  apps) (issue#4)