should reject -sysroot on darwin platforms

Cannot read /usr/local/Qt-5.7.1/plugins/platforms/libqios.prl: No such file or directory
Cannot read /usr/local/Qt-5.7.1/plugins/platforms/libqios.prl: No such file or directory

Ld PKDiagram.build/Debug-iphoneos/PKDiagram.build/Objects-normal/arm64/PKDiagram normal arm64
    cd /Users/patrick/Documents/dev/pkdiagram/build/ios
    export IPHONEOS_DEPLOYMENT_TARGET=6.0
    export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/Users/patrick/.rvm/gems/ruby-2.1.1/bin:/Users/patrick/.rvm/gems/ruby-2.1.1@global/bin:/Users/patrick/.rvm/rubies/ruby-2.1.1/bin:/Users/patrick/.pyenv/shims:/Users/patrick/bin/Sencha/Cmd/4.0.4.84:/usr/local/sbin:/usr/local/share/npm/bin:/usr/local/drush:/Library/PostgreSQL/9.1/bin:/usr/local/bin:/Users/patrick/pkaudio/bin:/Users/patrick/bin:/Users/patrick/Sites/res3d.com/depot_tools:/Applications/Postgres-9.2.2.0.app/Contents/MacOS/bin:/Users/patrick/Documents/dev/Sencha/android-sdk-macosx/tools:/Users/patrick/Documents/dev/Sencha/android-sdk-macosx/platform-tools:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/Users/patrick/.rvm/bin:/Users/patrick/dev/vendor/pyqt-sysroot-ios-64//bin"
  /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk -L/Users/patrick/Documents/dev/pkdiagram/build/ios/Debug-iphoneos -L/Users/patrick/Documents/dev/vendor/pyqt-sysroot-ios-64/lib/python3.5/site-packages -L/Users/patrick/Documents/dev/vendor/pyqt-sysroot-ios-64/lib/python3.5/site-packages/PyQt5 -L/Users/patrick/Documents/dev/vendor/pyqt-sysroot-ios-64/lib -L/usr/local/Qt-5.7.1/plugins/platforms -L/Users/patrick/dev/vendor/pyqt-sysroot-ios-64/usr/local/Qt-5.7.1/lib -L/Users/patrick/dev/vendor/pyqt-sysroot-ios-64/usr/local/Qt-5.7.1/lib -L/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk/System/Library/Frameworks -L/usr/local/Qt-5.7.1/plugins/imageformats -F/Users/patrick/Documents/dev/pkdiagram/build/ios/Debug-iphoneos -filelist /Users/patrick/Documents/dev/pkdiagram/build/ios/PKDiagram.build/Debug-iphoneos/PKDiagram.build/Objects-normal/arm64/PKDiagram.LinkFileList -miphoneos-version-min=6.0 -dead_strip -Xlinker -object_path_lto -Xlinker /Users/patrick/Documents/dev/pkdiagram/build/ios/PKDiagram.build/Debug-iphoneos/PKDiagram.build/Objects-normal/arm64/PKDiagram_lto.o -Xlinker -no_deduplicate -headerpad_max_install_names -stdlib=libc++ --sysroot=/Users/patrick/dev/vendor/pyqt-sysroot-ios-64/ -u _qt_registerPlatformPlugin -Wl,-e,_qt_main_wrapper -L/Users/patrick/Documents/dev/vendor/pyqt-sysroot-ios-64/lib/python3.5/site-packages -L/Users/patrick/Documents/dev/vendor/pyqt-sysroot-ios-64/lib/python3.5/site-packages/PyQt5 -L/Users/patrick/Documents/dev/vendor/pyqt-sysroot-ios-64/lib -L/usr/local/Qt-5.7.1/plugins/platforms -lqios -L/Users/patrick/dev/vendor/pyqt-sysroot-ios-64//usr/local/Qt-5.7.1/lib -framework MobileCoreServices -framework UIKit -framework OpenGLES -lz -lm -L/usr/local/Qt-5.7.1/plugins/imageformats -lqdds -lqicns -lqico -lqmacjp2 -lqtga -lqtiff -lqwbmp -lqwebp -lsip -lQt -lQtCore -lQtGui -lQtWidgets -lpython3.5 -lQt5Widgets -framework Foundation -framework CoreFoundation -framework CoreText -framework CoreGraphics -lQt5Gui -lqtpng -lqtharfbuzzng -lQt5Core -lqtpcre -Xlinker -dependency_info -Xlinker /Users/patrick/Documents/dev/pkdiagram/build/ios/PKDiagram.build/Debug-iphoneos/PKDiagram.build/Objects-normal/arm64/PKDiagram_dependency_info.dat -o /Users/patrick/Documents/dev/pkdiagram/build/ios/PKDiagram.build/Debug-iphoneos/PKDiagram.build/Objects-normal/arm64/PKDiagram
ld: framework not found MobileCoreServices
clang: error: linker command failed with exit code 1 (use -v to see invocation)