Easy Install requires a working build environment. This is installed by default on nearly all modern Linux distributions. Please make sure you have selected the “development tools” packages when you install or update your operating system.
If you want a Citadel installation which supports SSL encryption (recommended) you will need to install the development packages for OpenSSL. Use MCC to install these Packages:
kernel-devel, gcc-c++, gcc-cpp, make, libtool and gettext
thanks to bscmike for finding out.