profiles/ChangeLog-2011 contains: "Add net-dns/dnsmasq conntrack to package.use.mask on ppc64/64ul, arm and alpha as net-libs/libnetfilter_conntrack is not available." However, net-libs/libnetfilter_conntrack-1.0.4 is in fact marked stable for alpha, arm, arm64, ppc, and ppc64. The following lines: # mask conntrack USE flag for dnsmasq as dep is not keyworded net-dns/dnsmasq conntrack ...should be removed from these profile files: profiles/arch/alpha/package.use.mask profiles/arch/arm/package.use.mask profiles/arch/arm64/package.use.mask profiles/arch/powerpc/ppc64/64ul/package.use.mask It is unclear to me whether this mask can be removed from profiles/arch/nios2/package.use.mask.
This has been fixed in https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=04a440e96b979
alpha, arm, and powerpc are indeed fixed now, but the mask yet remains in arm64 despite net-libs/libnetfilter_conntrack-1.0.4 being keyworded arm64.
Cc'ing arm64
commit 5c1accf3f6e31d74bad17f666bba4e6fe0ad5374 (HEAD -> master, origin/master, origin/HEAD) Author: Alexis Ballier <aballier@gentoo.org> Date: Tue Jun 20 22:51:58 2017 +0200 profiles/arch/arm64: drop net-dns/dnsmasq conntrack, bug #585542 arm64 done