proxy-audio-device broken on El Capitan and below

[barracuda156]

Locally:

unknown option: -derivedDataPath
Usage: xcodebuild [-project <projectname>] [-activetarget] [-alltargets] [-target <targetname>]... [-parallelizeTargets] [-activeconfiguration] [-configuration <configurationname>] [-sdk <sdkfullpath>|<sdkname>] [<buildsetting>=<value>]... [<buildaction>]...
       xcodebuild [-version [-sdk <sdkfullpath>|<sdkname>]]
       xcodebuild [-showsdks]
       xcodebuild [-find <binary>] [-sdk <sdkfullpath>|<sdkname>]
       xcodebuild [-list]
Command failed: cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_audio_proxy-audio-device/proxy-audio-device/work/proxy-audio-device-1.0.6" && /usr/bin/xcodebuild -derivedDataPath ./DerivedData  -scheme "Proxy Audio Device Settings" -configuration Release install INSTALL_PATH=/Applications/MacPorts  OBJROOT="/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_audio_proxy-audio-device/proxy-audio-device/work/proxy-audio-device-1.0.6/build/" SYMROOT="/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_audio_proxy-audio-device/proxy-audio-device/work/proxy-audio-device-1.0.6/build/" MACOSX_DEPLOYMENT_TARGET=10.6 ARCHS=ppc SDKROOT="" GCC_VERSION=4.2 CLANG_CXX_LIBRARY="libstdc++" CODE_SIGN_IDENTITY= CODE_SIGNING_REQUIRED=NO DSTROOT="/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_audio_proxy-audio-device/proxy-audio-device/work/destroot"
Exit code: 1

Also broken on buildbots: ​https://ports.macports.org/port/proxy-audio-device/details