copy_gcc_libs() with multilib

[berney]

The current implementation of the copy_gcc_libs() helper function doesn't work for multilib systems.

kubler/engine/docker/bob-core/build-root.sh

Lines 59 to 70 in cc6ae36

	# Copy libgcc/libstdc++ libs
	function copy_gcc_libs() {
	local lib_gcc lib_gomp lib_stdc lib
	mkdir -p "${_EMERGE_ROOT}/${_LIB}"
	lib_gcc="$(find /usr/lib/ -name libgcc_s.so.1)"
	lib_gomp="$(find /usr/lib/ -name libgomp.so.1)"
	lib_stdc="$(find /usr/lib/ -name libstdc++.so.6)"
	for lib in "${lib_gcc}" "${lib_gomp}" "${lib_stdc}"; do
	cp "${lib}" "${_EMERGE_ROOT}/${_LIB}/"
	done
	}

The find commands will return multiple lines for the amd64 and x86 libraries, and the cp command will fail due to embedded newlines causing the file to not be found.

cp: cannot stat '/usr/lib/gcc/x86_64-pc-linux-gnu/14/libgcc_s.so.1'$'\n''/usr/lib/gcc/x86_64-pc-linux-gnu/14/32/libgcc_s.so.1': No such file or directory

I'm working on a PR to fix this.
However, one thing confusing me is the code use ${_EMERGE_ROOT}${_LIB}, and for amd64 this will be /emerge-root/lib64. So, the source will be /usr/lib/ and the destination will end up being /lib64/ (in the resulting container) - e.g no /usr/ and changes from just lib to lib64.

With merged-usr, /lib{,64} are symlinks to /usr/lib,{64}. But in the resulting container it won't be doing merged-usr symlinks.
The /etc/ld.so.conf doesn't contained the /lib{,64} directory. In my experiments it contains:

# contents of /etc/env.d directory.
include ld.so.conf.d/*.conf
# ld.so.conf autogenerated by env-update; make all changes to
/usr/lib
/usr/lib64
/usr/local/lib
/usr/local/lib64

Should copy_gcc_libs() be reproducing the /usr/lib{,64} directory structure?
Should the resulting containers be following the merged-usr layout with symlinks?
Or is it ok (safe) to change this to /lib{,64) (drop /usr/)?
If the /usr/ bit is dropped, should /etc/ld.so.conf be updated to include /lib{,64} (no /usr/) and /etc/ld.so.cache in /emerge_root be regenerated?