File _multibuild of Package darktable

<multibuild>
  <package>haswell</package>
  <package>broadwell</package>
  <package>ivybridge</package>
  <package>sandybridge</package>
  <package>skylake</package>
  <package>skylake-avx512</package>
  <package>znver2</package>
  <package>znver3</package>
  <package>asan</package>
</multibuild>