mgmt: compile osvinit after httpserver

Explicitly specify to the build system that the osvinit module needs
to be compiled after the httpserver module. Otherwise, we may randomly
get opposite order, and the compilation will fail.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>