Description of problem:

After fix of bug#1017604 32 bits versions of devtoolset libs located
in /opt/rh/devtoolset-9/root/usr/lib are added to $LD_LIBRARY_PATH together with 64 bits in /opt/rh/devtoolset-9/root/usr/lib64 when script is run in *64* bits environment.

However, should the opposite also be done?

Of course Devtoolset is 64 bits only, however to cross build 32 bits RPMS, something like the following is used:

$ setarch i686 rpmbuild -ba --target i668 foo.spec

Where foo.spec contains

%build
. /opt/rh/devtoolset-9/enable

%install
. /opt/rh/devtoolset-9/enable


The enable script uses the following call:

 rpmlibdir=$(rpm --eval "%{_libdir}")

and output from 

rpm --eval "%{_libdir}"

depend on arch:

$ setarch i686 rpm --eval %_libdir 
/usr/lib

$  rpm --eval %_libdir 
/usr/lib64

and this line:

export LD_LIBRARY_PATH=/opt/rh/devtoolset-9/root$rpmlibdir$rpmlibdir32:/opt/rh
/devtoolset-9/root$rpmlibdir/dyninst$rpmlibdir32/dyninst${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}

just add 32 bits versions.

If devtoolset-9-elfutils is installed, rpmbuild will use

/opt/rh/devtoolset-9/root/usr/bin/eu-strip

(to build debuginfor packages)

however, this will not work as it depend on libs in /opt/rh/devtoolset-9/root/usr/lib64, which is not added to $LD_LIBRARY_PATH.

To reproduce:

$ cat p.sh           
#! /bin/bash

set -x
. /opt/rh/devtoolset-9/enable
/opt/rh/devtoolset-9/root/usr/bin/eu-strip --version

$ setarch i686 ./p.sh
+ . /opt/rh/devtoolset-9/enable
++ export PATH=/opt/rh/devtoolset-9/root/usr/bin:/usr/sbin:/sbin:/usr/bin:/bin
++ PATH=/opt/rh/devtoolset-9/root/usr/bin:/home/trosten/bin:/usr/sbin:/sbin:/usr/bin:/bin
++ export MANPATH=/opt/rh/devtoolset-9/root/usr/share/man:
++ MANPATH=/opt/rh/devtoolset-9/root/usr/share/man:
++ export INFOPATH=/opt/rh/devtoolset-9/root/usr/share/info
++ INFOPATH=/opt/rh/devtoolset-9/root/usr/share/info
++ export PCP_DIR=/opt/rh/devtoolset-9/root
++ PCP_DIR=/opt/rh/devtoolset-9/root
+++ rpm --eval '%{_libdir}'
++ rpmlibdir=/usr/lib
++ '[' /usr/lib '!=' /usr/lib ']'
++ export LD_LIBRARY_PATH=/opt/rh/devtoolset-9/root/usr/lib
++ LD_LIBRARY_PATH=/opt/rh/devtoolset-9/root/usr/lib
++ export LD_LIBRARY_PATH=/opt/rh/devtoolset-9/root/usr/lib:/opt/rh/devtoolset-9/root/usr/lib/dyninst/dyninst:/opt/rh/devtoolset-9/root/usr/lib
++ LD_LIBRARY_PATH=/opt/rh/devtoolset-9/root/usr/lib:/opt/rh/devtoolset-9/root/usr/lib/dyninst/dyninst:/opt/rh/devtoolset-9/root/usr/lib
++ export PKG_CONFIG_PATH=/opt/rh/devtoolset-9/root/usr/lib64/pkgconfig
++ PKG_CONFIG_PATH=/opt/rh/devtoolset-9/root/usr/lib64/pkgconfig
+ /opt/rh/devtoolset-9/root/usr/bin/eu-strip --version
/opt/rh/devtoolset-9/root/usr/bin/eu-strip: error while loading shared libraries: libelf.so.dts.1: cannot open shared object file: No such file or directory

As 64 bits execution of /opt/rh/devtoolset-9/enable already adds 32 and 64 bits,
and 32 bits execution *should* also add both variants, logic can be simplified 
and both dirs added regardless of bits.