- spec-file-template: Do not try to build Spellchecker-plugin on CentOS/RedHat < 6, because the hunspell packages are only available from a thirdparty repo (atomicorp), therefore an automatic build is not possible and the users are forced to enable this repo.
Fix determining of redhat and fedora release-numbers.

git-svn-id: https://svn.code.sf.net/p/codeblocks/code/trunk@10053 2a5c6006-c6dd-42ca-98ab-0921f2732cef