The error is in the mkmf.log file. That file should be located at /home/hxh/.rvm/gems/ruby-1.9.3-p448/gems/linecache-0.46/ext/linecache/mkmf.log.
If not, you can use
sudo find / -name mkmf.log
to find it.
To troubleshoot further, see “How to install Nokogiri Ruby gem with mkmf.log saying libiconv not found?”