2015-01-12 13:59 GMT+01:00 mefyl <mefyl@gruntech.org>:
"clang++" "-arch" "arm64"  -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -gdwarf-2 -fexceptions -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Develop\
er/SDKs/iPhoneOS8.1.sdk -arch arm  -DBOOST_ALL_NO_LIB=1 -DBOOST_ATOMIC_STATIC_LINK=1 -DBOOST_CHRONO_STATIC_LINK=1 -DBOOST_CONTEXT_SOURCE -DBOOST_SYSTEM_NO_DEPRECATED -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_T\
HREAD_BUILD_LIB=1 -DBOOST_THREAD_POSIX -DBOOST_THREAD_USE_LIB=1 -DNDEBUG  -I"." -c -o "bin.v2/libs/context/build/darwin-4.2.1/release/address-model-64/architecture-arm/link-static/macosx-version-iphone-8.\
0/threading-multi/unsupported.o" "libs/context/src/unsupported.cpp"

libs/context/src/unsupported.cpp should not be selected - please take care that you use the version from github (branch develop).
Please note that you need to specify address-model, architecture, api and binary-format at cmd line if you do cross-compiling.