The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.
stdenv.targetPlatform really shouldn't be used by software that
doesn't generate or manipulate binaries. I reviewed all uses of
targetPlatform outside of pkgs/development/compilers and pkgs/stdenv
and replaced those which weren't involved in something which fits
these criteria.
The xdg-open utility is only ever a runtime dependency and its
dependents only expect that it accept a URI as a command line
argument and do something with it that the user would expect.
For such as a trivial relationship it should be possible for
users to override xdg-open with something else in their PATH.
