gnu: volk: Make retained references non-native inputs.

* gnu/packages/engineering.scm (volk)[native-inputs]:
Move python-wrapper and python-mako…
[inputs]: …here.

gnu/packages/engineering.scm

@@ -1057,9 +1057,8 @@ the 'showing the effect of'-style of operation.")
                    (,(string-append python "/bin:")))))
              #t)))))
     (inputs
-     `(("boost" ,boost)))
-    (native-inputs
-     `(("python" ,python-wrapper)
+     `(("boost" ,boost)
+       ("python" ,python-wrapper)
        ("python-mako" ,python-mako)))
     (home-page "https://www.libvolk.org/")
     (synopsis "Vector-Optimized Library of Kernels")