Since1b620d539c("kbuild: disable header exports for UML in a straightforward way"), installing headers fails on UML, so just disable installing them, since they're not needed anyway on the architecture. Fixes:b438b3b8d6("wireguard: selftests: support UML") Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>