互联网,我不知道该怎么做.升级到优胜美地后,我无法安装tiny_tds
$ gem install tiny_tds
Building native extensions. This could take a while...
ERROR: Error installing tiny_tds:
ERROR: Failed to build gem native extension.
/Users/jpolley/.rvm/rubies/ruby-2.1.1/bin/ruby extconf.rb
checking for iconv_open() in iconv.h... no
checking for iconv_open() in -liconv... no
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libiconv is missing.
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你能帮我吗？