在CentOS 5.6上安装完rvm并运行rvm notes后：
dependencies:
# For RVM
rvm: yum install -y bash curl git # NOTE: For git you need the EPEL repository enabled
# For Ruby (MRI & Ree) you should install the following OS dependencies:
ruby: yum install -y gcc-c++ patch readline readline-devel zlib zlib-devel libyaml-devel libffi-devel openssl-devel ;
yum install -y make bzip2 ;
yum install -y iconv-devel # NOTE: For centos 5.4 final iconv-devel might not be available :(
然而找不到iconv-devel：
Setting up Install Process
No package iconv-devel available.
Nothing to do
我应该如何安装它？