mk -s MOZ_MAKE_FLAGS=
Adding client.mk options from /Volumes/firefoxos/B2G/gonk-misc/default-gecko-config:
    AUTOCLOBBER=1
    export MOZ_AUTOMATION_BUILD_SYMBOLS=1
    export MOZ_AUTOMATION_L10N_CHECK=1
    export MOZ_AUTOMATION_PACKAGE=1
    export MOZ_AUTOMATION_PACKAGE_TESTS=1
    export MOZ_AUTOMATION_INSTALLER=0
    export MOZ_AUTOMATION_UPDATE_PACKAGING=0
    export MOZ_AUTOMATION_UPLOAD=1
    export MOZ_AUTOMATION_UPLOAD_SYMBOLS=0
    export MOZ_AUTOMATION_SDK=0
    CONFIG_GUESS=arm-linux-androideabi
    MOZ_OBJDIR=/Volumes/firefoxos/B2G/objdir-gecko
    OBJDIR=/Volumes/firefoxos/B2G/objdir-gecko
    FOUND_MOZCONFIG=/Volumes/firefoxos/B2G/gonk-misc/default-gecko-config
cd /Volumes/firefoxos/B2G/objdir-gecko
/Volumes/firefoxos/B2G/gecko/configure
Reexecuting in the virtualenv
Adding configure options from /Volumes/firefoxos/B2G/gonk-misc/default-gecko-config
  --enable-crashreporter
  --enable-release
  --enable-js-shell
  --target=arm-linux-androideabi
  --with-gonk=/Volumes/firefoxos/B2G
  --enable-application=b2g
  --with-android-ndk=/Users/mozilla/.mozbuild/android-ndk-r13
  --with-android-version=19
  --enable-debug-symbols
  --with-ccache
  --disable-printing
  --disable-crashreporter
  --with-fpu=neon
  --enable-profiling
  --with-ccache
  CXXFLAGS=-DMOZ_ENABLE_JS_DUMP -include /Volumes/firefoxos/B2G/gonk-misc/Unicode.h
  MOZ_ADDON_SIGNING=1
  MOZ_REQUIRE_SIGNING=0
  ENABLE_TESTS=1
  ENABLE_MARIONETTE=1
checking for a shell... /bin/sh
checking for host system type... x86_64-apple-darwin15.6.0
checking for target system type... arm-unknown-linux-androideabi
checking for the Android toolchain directory... /Users/mozilla/.mozbuild/android-ndk-r13/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64
checking whether cross compiling... yes
checking for pkg_config... not found
checking for tar... /usr/local/bin/gtar
checking for unzip... /usr/bin/unzip
checking for zip... /usr/bin/zip
checking for the Mozilla API key... no
checking for the Google API key... no
checking for the Bing API key... no
checking for the Adjust SDK key... no
checking for yasm... /usr/local/bin/yasm
checking yasm version... 1.3.0
checking for android platform directory... /Users/mozilla/.mozbuild/android-ndk-r13/platforms/android-19/arch-arm
checking for ccache... /usr/local/bin/ccache
checking for the target C compiler... /Users/mozilla/.mozbuild/android-ndk-r13/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-gcc
checking whether the target C compiler can be used... yes
checking the target C compiler version... 4.9.0
checking the target C compiler works... yes
checking for the target C++ compiler... /Users/mozilla/.mozbuild/android-ndk-r13/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-g++
checking whether the target C++ compiler can be used... yes
checking the target C++ compiler version... 4.9.0
checking the target C++ compiler works... yes
checking for the host C compiler... /usr/bin/clang
checking whether the host C compiler can be used... yes
checking the host C compiler version... 5.1.0
checking the host C compiler works... yes
checking for the host C++ compiler... /usr/bin/clang++
checking whether the host C++ compiler can be used... no
DEBUG: <truncated - see config.log for full output>
DEBUG: | #elif __linux__
DEBUG: | %KERNEL "Linux"
DEBUG: | #elif _WIN32 || __CYGWIN__
DEBUG: | %KERNEL "WINNT"
DEBUG: | #elif __NetBSD__
DEBUG: | %KERNEL "NetBSD"
DEBUG: | #elif __APPLE__
DEBUG: | %KERNEL "Darwin"
DEBUG: | #endif
DEBUG: | #if _MSC_VER || __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
DEBUG: | %ENDIANNESS "little"
DEBUG: | #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
DEBUG: | %ENDIANNESS "big"
DEBUG: | #endif
DEBUG: Executing: `/usr/local/bin/ccache /usr/bin/clang++ -std=gnu++11 -E /var/folders/23/7zydwv9x7td824c4jh9c_8rc0000gn/T/conftest.Gzc4jp.cpp`
DEBUG: COMPILER = clang
DEBUG: cplusplus = 201103L
DEBUG: CPU = x86_64
DEBUG: KERNEL = Darwin
DEBUG: ENDIANNESS = little
ERROR: Only clang/llvm 3.6 or newer is supported.
*** Fix above errors and then restart with               "/Applications/Xcode-5.1.1/Xcode.app/Contents/Developer/usr/bin/make -f client.mk build"
make[3]: *** [configure] Error 1
make[2]: *** [/Volumes/firefoxos/B2G/objdir-gecko/Makefile] Error 2
make[1]: *** [build] Error 2
make: *** [out/target/product/aries/obj/DATA/gecko_intermediates/gecko] Error 2

real	2m38.710s
user	1m7.267s
sys	1m24.716s

> Build failed! <

Build with |./build.sh -j1| for better messages
If all else fails, use |rm -rf objdir-gecko| to clobber gecko and |rm -rf out| to clobber everything else.