The list is onyl for convenience, you always can add the mcu flag by hand in the compiler options of the project....
About your problem in linux, how do you have installed codeblocks? Some kind of installations can lead to codeblocks being installed as sudo so you can not modify the file by non sudo user
BUT NOTHING in the processors list
What list are you talking about? The list in the new project wizard, or the list in the compiler settings?
How do you install codeblocks on windows? The different installation methods lead to different search paths for the files...
PS. i till try to update the list