问如何在10.10Yosemite上安装therubyracer gem？

EN

11:53  $ gem install libv8 -v '3.16.14.3' -- --with-system-v8


Building native extensions with: '--with-system-v8'
This could take a while...
Successfully installed libv8-3.16.14.3
Parsing documentation for libv8-3.16.14.3
Installing ri documentation for libv8-3.16.14.3
Done installing documentation for libv8 after 0 seconds
1 gem installed


02:05  $ gem install therubyracer -v '0.12.1' -- --with-system-v8


Building native extensions with: '--with-system-v8'
This could take a while...
ERROR:  Error installing therubyracer:
    ERROR: Failed to build gem native extension.

    /usr/local/var/rbenv/versions/2.1.2/bin/ruby extconf.rb --with-system-v8
checking for main() in -lpthread... yes
checking for main() in -lobjc... yes
checking for v8.h... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/local/var/rbenv/versions/2.1.2/bin/ruby
    --with-pthreadlib
    --without-pthreadlib
    --with-objclib
    --without-objclib
    --enable-debug
    --disable-debug
    --with-v8-dir
    --without-v8-dir
    --with-v8-include
    --without-v8-include=${v8-dir}/include
    --with-v8-lib
    --without-v8-lib=${v8-dir}/lib
/usr/local/var/rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.16.14.3/ext/libv8/location.rb:50:in `configure': You have chosen to use the version of V8 found on your system (Libv8::Location::System::NotFoundError)
and *not* the one that is bundle with the libv8 rubygem. However,
it could not be located. please make sure you have a version of
v8 that is compatible with 3.16.14.3 installed. You may
need to special --with-v8-dir options if it is in a non-standard
location

thanks,
The Mgmt

    from /usr/local/var/rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.16.14.3/lib/libv8.rb:7:in `configure_makefile'
    from extconf.rb:32:in `'

extconf failed, exit code 1

Gem files will remain installed in /usr/local/var/rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/therubyracer-0.12.1 for inspection.
Results logged to /usr/local/var/rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/extensions/x86_64-darwin-14/2.1.0-static/therubyracer-0.12.1/gem_make.out