mir: fix warnings with PerMachine move-constructor

This is a legit issue, not only was the target being initialized first,
but both the host and the target values were moving the target field
from the other one. This last part is obviously really bad.

src/mir/meson/machines.hpp

@@ -73,8 +73,7 @@ template <typename T> class PerMachine {
         : _build{std::move(_b)}, _host{std::move(_h)}, _target{std::nullopt} {};
     PerMachine(T && _b) : _build{std::move(_b)}, _host{std::nullopt}, _target{std::nullopt} {};
     PerMachine(PerMachine<T> && t) noexcept
-        : _build{std::move(t._build)}, _target{std::move(t._target)},
-          _host{std::move(t._target)} {};
+        : _build{std::move(t._build)}, _host{std::move(t._host)}, _target{std::move(t._target)} {};
     ~PerMachine() = default;
 
     PerMachine<T> & operator=(PerMachine<T> && t) noexcept {