fixes in stable-5.00

[gottaeat]

• moved variables after make in headers_check and headers_install steps, otherwise the cross-tools kernel headers won't get installed under /cross-tools/${MLFS_TARGET}.
• added the missing esac in the toolchain adjusting step for cross-tools.
• when building lzip, configure doesn't update the CXX flag, causing the make to build with the host g++. added a sed command to manullay change g++ to ${MLFS_TARGET}-g++.
• bzip2 recipe for the final system is missing the ../patches prefix when patching, fixed that.
• musl-fts and musl-obstack recipes have make & make install, which causes make to install before build finishes, resulting in a make error, fixed that.
• removed the ~ character at the end of meson build recipe for the final system.
• final system groff recipe mentions the page size only for the united states letter size, added statement about the A4 size.
• fixed typo in the installation of the final system iproute and updated the package source to 5.2.0 from 5.1.0.
• instructions for eudev mentions udev-lfs-20171102.tar.xz but nothing points to the source link, added it.
• added disclaimer about the /tools and /cross-tools, it is safe to delete them after the build is done as they're not needed anymore.

with these changes, i was able to build and boot properly to a working musl+libressl system. i didn't test porg or anything related to s6 and its tools since i don't use porg and replaced s6 with sysvinit and my own set of init scripts.

[dslm4515]

These fixes look good. I made scripts to semi-automate the build for '/cross-tools' and '/tools' ... I will upload soon.