installing hpricot
===

I'm trying to install `hpricot` and am getting the following error. I do have xcode installed but I'm not sure what else I'm missing.


    $ gem install hpricot
    Building native extensions.  This could take a while...
    ERROR:  Error installing hpricot:
    	ERROR: Failed to build gem native extension.
    
            /Users/user_name/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb
    checking for stdio.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.

