lib/functions.in: fixed split_debug_files() to skip processing of static libary archives
lib/functions.in: improved split_debug_files() to check earlier if we need to skip the processing of the file according to the file name
lib/functions.in: improved split_debug_files() to chmod 644 the generated debug info file
debug split: move check for enabling debug symbol splitting from functions.in into Build-Pkg

The check will be run right after the postinstall hook and before
creating the flist.
Build-Pkg: changed to disable debug symbol splitting for kernel packages