Log Message:
libproxy: update to 0.5.1.

What's Changed

    Guard PxManager test with pacrunner-duktape option by @janbrummer in #215
    Fix build on NetBSD. by @0-wiz-0 in #220
    Install libpxbackend into pkglibdir by @amigadave in #223
    Move glib2 inclusion out of c++ protection. by @0-wiz-0 in #227
    Replace libsoup with glib socket service functions by @janbrummer in #228
    Enforce online state for tests by @janbrummer in #229
    Use glib-object header instead of gio by @janbrummer in #230
    Fix libproxy rpath by @janbrummer in #231
    Draft: Improve ignore checks by @janbrummer in #232
    Release 0.5.1 by @janbrummer in #233