/usr/local/bin/ruby extconf.rb 
extconf.rb:131: warning: mismatched indentations at 'end' with 'unless' at 125
extconf.rb:18:Warning: Gem::SourceIndex#search support for String patterns is deprecated, use #find_name
checking for atan() in -lm... no
checking for atan() in -lm... yes
checking for inflate() in -lz... yes
checking for xmlXPtrNewRange() in -lxml2... yes
checking for libxml/xmlversion.h... no
checking for libxml/xmlversion.h in /opt/include/libxml2,/usr/local/include/libxml2,/usr/include/libxml2... yes
checking for xsltApplyStylesheet() in -lxslt... yes
checking for xslt.h... no
checking for xslt.h in /opt/include/libxslt,/usr/local/include/libxslt,/usr/include/libxslt... yes
checking for exsltLibexsltVersion() in -lexslt... yes
checking for exslt.h... no
checking for exslt.h in /opt/include/libexslt,/usr/local/include/libexslt,/usr/include/libexslt... yes
checking for libxml/ruby_libxml.h... yes
checking for libxml/ruby_xml_document.h... yes
checking for rxml_document_wrap() in -lxml_ruby... no
checking for rxml_document_wrap() in -l:libxml_ruby.so... no
*** 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=/usr/local/bin/ruby
	--with-xml2-dir
	--without-xml2-dir
	--with-xml2-include
	--without-xml2-include=${xml2-dir}/include
	--with-xml2-lib
	--without-xml2-lib=${xml2-dir}/lib
	--with-xslt-dir
	--without-xslt-dir
	--with-xslt-include
	--without-xslt-include=${xslt-dir}/include
	--with-xslt-lib
	--without-xslt-lib=${xslt-dir}/lib
	--with-exslt-dir
	--without-exslt-dir
	--with-exslt-include
	--without-exslt-include=${exslt-dir}/include
	--with-exslt-lib
	--without-exslt-lib=${exslt-dir}/lib
	--with-libxml-ruby-dir
	--without-libxml-ruby-dir
	--with-libxml-ruby-include
	--without-libxml-ruby-include=${libxml-ruby-dir}/include
	--with-libxml-ruby-lib
	--without-libxml-ruby-lib=${libxml-ruby-dir}/lib
	--with-mlib
	--without-mlib
	--with-mlib
	--without-mlib
	--with-zlib
	--without-zlib
	--with-xml2lib
	--without-xml2lib
	--with-xsltlib
	--without-xsltlib
	--with-exsltlib
	--without-exsltlib
	--with-xml_rubylib
	--without-xml_rubylib
	--with-:libxml_ruby.solib
	--without-:libxml_ruby.solib
 extconf failure: %s
  need libxml-ruby
        Install libxml-ruby first.