Turn OpenSSL into a virtual package

Hello,

So, we finally applied this series, but with quite a few changes:

- We were not happy with carrying all those patches to make those packages compatible with LibreSSL, so instead we made them depend on libopenssl only.

- For heirloom-mailx, we kept the patch because it looks acceptable upstream. Could you submit it upstream, please?

- For softether, switching to a "depends on" was not acceptable, as it would break existing defconfigs. So instead, we introduced a BR2_PACKAGE_OPENSSL_FORCE_LIBOPENSSL hidden boolean that tells the openssl virtual package that only libopenssl is acceptable as a provider.

- With your series, ca-certificates would not build, because it needs host-openssl, which would be host-libressl, which doesn't exist. However, using host-libressl would mean that all packages that depend on host-openssl would have to be checked. So instead, we defined BR2_PACKAGE_PROVIDES_HOST_OPENSSL to host-libopenssl, which forces host-openssl to always point to host-libopenssl.

With those changes, series applied. Now, it would be helpful to update utils/genrandconfig to randomly enable libressl instead of openssl to get this situation tested by the autobuilders.

Thanks a lot!

Thomas

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com