title: Can't install ruby gem johnson
body: <p>I am trying to install on ruby 1.8.7 the johnson 2.0.0pre3 gem and I am getting this compilation error: </p>
  
  <pre><code>(stable)$ gem install johnson -v '2.0.0pre3'
  Building native extensions.  This could take a while...
  ERROR:  Error installing johnson:
      ERROR: Failed to build gem native extension.
  
      /Users/aaa/.rvm/rubies/ruby-1.8.7-p374/bin/ruby extconf.rb
  creating cache ./config.cache
  checking host system type... x86_64-apple-darwin12.5.0
  checking target system type... x86_64-apple-darwin12.5.0
  checking build system type... x86_64-apple-darwin12.5.0
  checking for mawk... no
  checking for gawk... no
  checking for nawk... no
  checking for awk... awk
  checking for gcc... gcc
  checking whether the C compiler (gcc  ) works... yes
  checking whether the C compiler (gcc  ) is a cross-compiler... no
  checking whether we are using GNU C... yes
  checking whether gcc accepts -g... yes
  checking for c++... c++
  checking whether the C++ compiler (c++  ) works... yes
  checking whether the C++ compiler (c++  ) is a cross-compiler... no
  checking whether we are using GNU C++... yes
  checking whether c++ accepts -g... yes
  checking for ranlib... ranlib
  checking for as... /usr/bin/as
  checking for ar... ar
  checking for ld... ld
  checking for strip... strip
  checking for windres... no
  checking whether gcc and cc understand -c and -o together... yes
  checking how to run the C preprocessor... gcc -E
  checking how to run the C++ preprocessor... c++ -E
  checking for a BSD compatible install... /usr/bin/install -c
  checking whether ln -s works... yes
  checking for perl5... no
  checking for perl... /usr/bin/perl
  checking for minimum required perl version &gt;= 5.006... 5.012004
  checking for full perl installation... yes
  checking for python... /usr/bin/python
  checking for doxygen... :
  checking for whoami... /usr/bin/whoami
  checking for autoconf... /usr/local/bin/autoconf
  checking for unzip... /usr/bin/unzip
  checking for zip... /usr/bin/zip
  checking for makedepend... /opt/X11/bin/makedepend
  checking for xargs... /usr/bin/xargs
  checking for pbbuild... no
  checking for xcodebuild... /usr/bin/xcodebuild
  ./configure: line 3686: test: Xcode 5.0.2 Build version 5A3005: integer expression expected
  checking for sdp... :
  checking for gmake... no
  checking for make... /usr/bin/make
  checking for X... no
  checking whether the compiler supports -Wno-invalid-offsetof... yes
  checking whether the compiler supports -Wno-variadic-macros... yes
  checking whether ld has archive extraction flags... no
  checking that static assertion macros used in autoconf tests work... yes
  checking for 64-bit OS... yes
  checking for -dead_strip option to ld... yes
  checking for ANSI C header files... yes
  checking for working const... yes
  checking for mode_t... yes
  checking for off_t... yes
  checking for pid_t... yes
  checking for size_t... yes
  checking for st_blksize in struct stat... yes
  checking for siginfo_t... yes
  checking for stdint.h... yes
  checking for the size of void*... configure: error: No size found for void*
  *** 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/aaa/.rvm/rubies/ruby-1.8.7-p374/bin/ruby
  extconf.rb:27: could not run configure (RuntimeError)
      from extconf.rb:23:in `chdir'
      from extconf.rb:23
  
  
  Gem files will remain installed in /Users/aaa/.rvm/gems/ruby-1.8.7-p374/gems/johnson-2.0.0.pre3 for inspection.
  Results logged to /Users/aaa/.rvm/gems/ruby-1.8.7-p374/gems/johnson-2.0.0.pre3/ext/tracemonkey/gem_make.out
  </code></pre>
  
  <p>What can cause this?
  Thank you!</p>