gem install ruby_kml - failed to build native extension -- Mac with OSX 10.9.4, ruby 1.9.3

[larrytalley]

Trying to install on my Mac with OSX 10.9.4, Ruby 1.9.3p448:

gem install ruby_kml Building native extensions. This could take a while... Building nokogiri using packaged libraries. ERROR: Error installing ruby_kml: ERROR: Failed to build gem native extension.

/Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/bin/ruby extconf.rb

Building nokogiri using packaged libraries. checking for iconv.h... *** 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 --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/ltalley/.rvm/rubies/ruby-1.9.3-p448/bin/ruby --help --clean --use-system-libraries --enable-static --disable-static --with-zlib-dir --without-zlib-dir --with-zlib-include --without-zlib-include=${zlib-dir}/include --with-zlib-lib --without-zlib-lib=${zlib-dir}/lib --enable-cross-build --disable-cross-build /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:381:in try_do': The compiler failed to generate an executable file. (RuntimeError) You have to install development tools first. from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:506:intry_cpp' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:931:in block in have_header' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:790:inblock in checking_for' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:284:in block (2 levels) in postpone' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:254:inopen' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:284:in block in postpone' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:254:inopen' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:280:in postpone' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:789:inchecking_for' from /Users/ltalley/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/mkmf.rb:930:in have_header' from extconf.rb:103:inhave_iconv?'