Revert "gnu: m4-boot0: Downgrade to 1.4.18."

This reverts commit 9cdb5e7f8f.

This version FTBFS on powerpc64le-linux.

gnu/packages/commencement.scm

@@ -3356,35 +3356,12 @@ (define m4-boot0
   (package
     (inherit m4)
     (name "m4-boot0")
-    (version "1.4.18")
+    (source (bootstrap-origin (package-source m4)))
-    (source (origin
-              (method url-fetch)
-              (uri (string-append "mirror://gnu/m4/m4-" version ".tar.gz"))
-              (sha256
-               (base32 "1arz972zxmwhnyik9007g6ww9gars8d55xbvg548xlsw3a9369mb"))))
     (inputs (%boot0-inputs))
     (arguments
      `(#:guile ,%bootstrap-guile
        #:implicit-inputs? #f
-       #:phases
+       ,@(package-arguments m4)
-       (modify-phases %standard-phases
-         (add-before 'check 'pre-check
-           (lambda* (#:key inputs #:allow-other-keys)
-             (for-each patch-shebang (find-files "tests" "\\.sh$"))
-             (substitute* (find-files "tests" "posix_spawn")
-               (("/bin/sh")
-                (search-input-file inputs "/bin/sh")))))
-         ;; Better to skip some tests instead of all the tests.
-         ,@(if (target-riscv64?)
-               `((add-after 'unpack 'skip-some-tests
-                   (lambda _
-                     (substitute* "tests/Makefile.in"
-                       (("test-canonicalize-lgpl\\$\\(EXEEXT\\) ") "")
-                       (("test-localename\\$\\(EXEEXT\\) ") "")
-                       (("test-mbrtowc5.sh ") "")
-                       (("test-sigprocmask\\$\\(EXEEXT\\) ") "")
-                       ))))
-               `()))
        ;; Ignore test failure in gnulib for armhf/aarch64 and Hurd
        #:tests? ,(and (not (target-arm?))
                       (not (target-hurd?)))))))