I tried to add answer to https://boinc.berkeley.edu/dev/forum_thread.php?id=10895, but that thread is locked, so I am creating a new one.

I have found on Odroid forum that it is possible to add repository for another architecture. Following commands will install 32-bit libs needed to run most BOINC apps:

sudo dpkg --add-architecture armhf
sudo apt-get update
sudo apt-get install libc6:armhf libstdc++6:armhf

Additionally you have to add alternate platform identifier to your cc_config.xml file:

<cc_config>
    <options>
        <alt_platform>arm-unknown-linux-gnueabihf</alt_platform>
    </options>
</cc_config>

After doing this, BOINC will be able to download and run 32-bit ARM apps on 64-bit ARM devices. Happy crunching :)

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This solution may not apply to all ARM systems. The linked thread specifically mentions the Raspberry3 which has a 32bit kernel and OS and can't execute 64bit executables. The Odroids on the other hand have a 64bit kernel and operating system and there you need the multilib support in order to execute 32bit executables.