You can prove that this problem is not due to missing non-UTF support by doing as I just did:
Open the file Editor.cxx in SciTE, and save 5 separate copies of the same file, each using a different encoding method. Then drag all these files onto Code::Blocks.
You will see that it opens none of them, regardless of whether they are 8-bit encoded, UTF-8 encoded with or without cookie, or UCS-2 encoded in either big or little endian (the latter is not surprising, UCS-2 is indeed not supported).
It does not matter how this particular file is encoded, it does not work either way.
Obviously there is a (yet unknown) issue with certain files, but it is certainly not "Code::Blocks has no support for opening non-UTF files".