package/casync-nano: enable OpenSSL ChaCha20 support
When building against OpenSSL, ensure the ChaCha20 algorithm is enabled,
which is needed by this package.
Fixes: https://autobuild.buildroot.org/results/3cb/3cb58229dfb47e79c50b4b52ca57b3f56a945ed7
Signed-off-by: Florian Larysch <fl@n621.de>
Signed-off-by: Julien Olivain <ju.o@free.fr>