hostapd: convert ssl provider build options to variants

hostapd: convert ssl provider build options to variants

Instead of selecting the SSL provider at compile time, build package
variants for each option so users can select the binary package without
having to build it themselves.
Most likely not all variants have actually ever been user by anyone.
We should reduce the selection to the reasonable and most used
combinations at some point in future. For now, build them all.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(backported from c8fdd0e9c843dd483f6677dc41f7df17313aa3cd)