Avoid 'package-with-c-toolchain' effect.

* function-multi-versioning.scm (fmv-patched-package): Remove
'package-with-c-toolchain' call.

function-multi-versioning.scm

@@ -261,13 +261,11 @@ TOOLCHAIN to obtain vectorization info."
 
 (define* (fmv-patched-package p #:key (toolchain latest-toolchain))
   "Return package P patched to contain multi-versioned functions."
-  (package-with-c-toolchain
-   (package/inherit p
-     (source (origin
-               (inherit (package-source p))
-               (patches (cons (fmv-patch p #:toolchain toolchain)
-                              (origin-patches (package-source p)))))))
-   toolchain))
+  (package/inherit p
+    (source (origin
+              (inherit (package-source p))
+              (patches (cons (fmv-patch p #:toolchain toolchain)
+                             (origin-patches (package-source p))))))))
 
 
 ;; Return the patched package.