gnulib: remove use of 'byteswap' module

Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NPeter Krempa <pkrempa@redhat.com>

bootstrap.conf

@@ -20,7 +20,6 @@
 gnulib_modules='
 accept
 bind
-byteswap
 c-ctype
 c-strcase
 c-strcasestr