linecache19 in 1.9.2-head

rvm install 1.9.2-head
rvm use 1.9.2-head

[jc@macbookpro ~]# gem install linecache19
Building native extensions.  This could take a while...
ERROR:  Error installing linecache19:
	ERROR: Failed to build gem native extension.

/Users/jc/.rvm/rubies/ruby-1.9.2-head/bin/ruby extconf.rb
checking for vm_core.h... no
Makefile creation failed
*************************************************************

  NOTE: For Ruby 1.9 installation instructions, please see:

     http://wiki.github.com/mark-moseley/ruby-debug

*************************************************************

*** 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/jc/.rvm/rubies/ruby-1.9.2-head/bin/ruby
	--with-ruby-dir
	--without-ruby-dir
	--with-ruby-include
	--without-ruby-include=${ruby-dir}/include
	--with-ruby-lib
	--without-ruby-lib=${ruby-dir}/lib
Requesting http://cloud.github.com/downloads/mark-moseley/ruby_core_source/preview_revision.yml
Downloading http://cloud.github.com/downloads/mark-moseley/ruby_core_source/preview_revision.yml


Gem files will remain installed in /Users/jc/.rvm/gems/ruby-1.9.2-head/gems/linecache19-0.5.11 for inspection.
Results logged to /Users/jc/.rvm/gems/ruby-1.9.2-head/gems/linecache19-0.5.11/ext/trace_nums/gem_make.out