this is a million times faster
new only in rust 1.68, and fails on older versions,
but we have only latest in aports and don't support anything else, so
it's okay.
The cargo vars are now set in abuild.conf by default.
Newlines done with:
find . -name APKBUILD -exec sed -i '/^$/N;/^\n$/D' {} \;
See also: https://stackoverflow.com/a/4522043
