Add instructions to copy to SRC_ARCHIVE in func_install_blfs, so that files
are kept in host repo, and not downloaded again, should a new build be
started.
when the user fstab and/or kernel config are the same as the ones in
$BUILDDIR/sources: avoid to cp on itself
- set SRC_ARCHIVE=/dev/null in BLFS tools download script if SRC_ARCHIVE is
empty
- Remove the download part of the book instruction for cacerts
- Separate download and md5sum instructions in "download-script" generation,
so that packages with no md5sum can still be downloaded.
- Add --preserve-timestamps when copying the local BLFS book working copy
so that if the book has already been validated it is not validated again
- Some scriptlet changes are not needed anymore
