gemでのraindropsのインストールでトラブル

snowleopardな環境でgem install raindropsが以下な感じでこける

shell$ gem install raindrops -v '0.8.0' --no-rdoc --no-ri
Building native extensions.  This could take a while...
ERROR:  Error installing raindrops:
	ERROR: Failed to build gem native extension.

        /Users/paco/.rbenv/versions/1.9.3-p0/bin/ruby extconf.rb
checking for mmap() in sys/mman.h... yes
checking for munmap() in sys/mman.h... yes
checking for mremap() in sys/mman.h... no
checking for getpagesize() in unistd.h... yes
checking for rb_thread_blocking_region()... yes
checking for rb_thread_io_blocking_region()... yes
checking for GCC 4+ atomic builtins... no
checking for atomic_ops.h... no

libatomic_ops is required if GCC 4+ is not used.
See http://www.hpl.hp.com/research/linux/atomic_ops/

Users of Debian-based distros may run:

  apt-get install libatomic-ops-dev
*** 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=/Users/paco/.rbenv/versions/1.9.3-p0/bin/ruby
	--with-atomic_ops-dir
	--without-atomic_ops-dir
	--with-atomic_ops-include
	--without-atomic_ops-include=${atomic_ops-dir}/include
	--with-atomic_ops-lib
	--without-atomic_ops-lib=${atomic_ops-dir}/lib

http://www.hpl.hp.com/research/linux/atomic_ops/download.php4よりソースを引っ張ってきて（めんどくさいので最新版を）以下の感じでコンパイル。

CC=gcc-4.2 ./configure 
make
make install

でライブラリを入れたのちもう一度コマンドを打ってみたらgemが入った（動作確認を取ってないから動くかはまだ見検証）