krb5: Move debugging files to the debug package

Resolve the following errors:
  ERROR: QA Issue: non debug package contains .debug directory: krb5 path /work/x86_64-maui-linux/krb5/1.8.5-r0/packages-split/krb5/usr/lib/krb5/plugins/kdb/.debug/db2.so
  ERROR: QA Issue: non debug package contains .debug directory: krb5 path /work/x86_64-maui-linux/krb5/1.8.5-r0/packages-split/krb5/usr/lib/krb5/plugins/preauth/.debug/encrypted_challenge.so
  ERROR: QA Issue: non debug package contains .debug directory: krb5 path /work/x86_64-maui-linux/krb5/1.8.5-r0/packages-split/krb5/usr/lib/krb5/plugins/preauth/.debug/pkinit.so