gnu: rust: Build with Make 4.2.

Fixes <https://bugs.gnu.org/39949>.

* gnu/packages/rust.scm (rust-1.20)[native-inputs]: Add GNU-MAKE-4.2.

gnu/packages/rust.scm

@@ -469,6 +469,10 @@ safety and thread safety guarantees.")
                       (delete-file-recursively "src/llvm")
                       #t))
           (patches '())))
+      (native-inputs
+       `(;; The tests fail with newer versions of GNU Make.
+         ("make" ,gnu-make-4.2)
+         ,@(package-native-inputs base-rust)))
       (outputs '("out" "doc" "cargo"))
       ;; Since rust-1.19 is local, it's quite probable that Hydra
       ;; will build rust-1.19 only as a dependency of rust-1.20.