Using readline can improve line editing feature of bc, but it's not
enabled by default.
As readline is already installed before bc, let's pick up this
improvement with no cost.
Update to iana-etc-20210304.
Update to zstd-1.4.9.
Update to sysvinit-2.99.
Update to linux-5.11.6.
Update to libcap-2.49.
Update to iproute2-5.11.0.
Update to e2fsprogs-1.46.2.
Update to bison-3.7.6.
Update to bc-3.3.3.
Update to attr-2.5.0.
Update to acl-2.3.0.
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@12164 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
Update to iana-etc-20210115.
Update to bc-3.2.5.
Update to e2fsprogs-1.46.0.
Update to autoconf-2.71.
Update to tzdata-2021a.
Update to perl-5.32.1.
Update to libcap-2.47.
Update to bison-3.7.5.
Update to binutils-2.36. Requires building zlig in Chapter 6.
Update to linux-5.10.12.
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@12105 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689