The current package for couchdb for aarch64 is at version 1.6.1 and it does not work with icu 58. The PKGBUILD used (as in the packages section inside archlinux arm website) is the same one for x86/x86-64, however makepkg fails with:
$this->bbcode_second_pass_code('', '
cc: error: unrecognized command line option '-m64'
')
This happens because couchdb ships with an old version of rebar (an erlang dependency manager) that has a bug regarding arm64 (https://github.com/rebar/rebar/issues/536). Downloading the latest version of rebar (https://github.com/rebar/rebar/wiki/rebar) and placing it in bin/rebar (relative to the couchdb sources) fixes the problem: makepkg now runs fine. For what I have understood, the PKGBUILD needs to be forked in (https://github.com/archlinuxarm/PKGBUILDs), but issues on that repository are not enabled. I'm writing this here in order to help the package mantainers.