By computing this value outside the build code, new targets
can be added without causing rebuilds for other targets.

* gnu/packages/tls.scm
  (target->openssl-target): New procedure.
  (openssl)[arguments]<#:phases>{set-cross-compile}: Use it.
---
 gnu/packages/tls.scm | 46 ++++++++++++++++++++++++++------------------
 1 file changed, 27 insertions(+), 19 deletions(-)