Revert "Set these unconditionally for wrap_vga"

This reverts commit 09471908e37743da1eeb20fe9568e166d4a389a7.
Revert "Make sure BUILD_KERNELS also includes the wrap_vga kernel"

This reverts commit 118dcec81598fa0fec44a08dc64e2c312c3fb3bd.
Make sure _VGA is initialized
Fix nanobsd with vga build and restore variables after it