Irrlicht is autodetected if it is installed in /usr or /usr/local on linux
font_tool work (well, it does not work because there are some compilation error due to system specific libs I think, but I have it working if I change some code in src/font_tool/main.cpp, but I don't want to commit my modifications since I am not sure what this tool should do).
Detect when a library is not present and put an error when it is the cases.
Some paths change to have it working on out of source builds too.
Remove the DEBUG option, since cmake has already one to do that, -DCMAKE_BUILD_TYPE=Debug
Let me know if there are any problem/regressions with it, or just revert ;)
git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@9405 178a84e3-b1eb-0310-8ba1-8eac791a3b58