gnu: multipath-tools: Remove input labels.

* gnu/packages/linux.scm (multipath-tools)[arguments]: Use G-expression and
SEARCH-INPUT-FILE.
[inputs]: Remove labels.

gnu/packages/linux.scm

@@ -5223,34 +5223,31 @@ arrays when needed.")
                   #t))))
     (build-system gnu-build-system)
     (arguments
-     '(#:test-target "test"
+     (list
-       #:parallel-build? #f             ;XXX: broken in 0.8.4
+      #:test-target "test"
-       #:make-flags (list "CC=gcc"
+      #:parallel-build? #f              ;XXX: broken since 0.8.4
-                          (string-append "DESTDIR="
+      #:make-flags #~(list (string-append "CC=" #$(cc-for-target))
-                                         (assoc-ref %outputs "out"))
+                           (string-append "DESTDIR=" #$output)
                            ;; Install Udev rules below this directory, relative
                            ;; to the prefix.
                            "SYSTEMDPATH=lib"
-                          (string-append "LDFLAGS=-Wl,-rpath="
+                           (string-append "LDFLAGS=-Wl,-rpath=" #$output "/lib"))
-                                         (assoc-ref %outputs "out")
-                                         "/lib"))
       #:phases
-       (modify-phases %standard-phases
+      #~(modify-phases %standard-phases
           (add-after 'unpack 'patch-source
             (lambda* (#:key inputs #:allow-other-keys)
-             (let ((lvm2 (assoc-ref inputs "lvm2"))
+              (let ((libdevmapper.h
-                   (udev (assoc-ref inputs "udev")))
+                     (search-input-file inputs "include/libdevmapper.h"))
+                    (libudev.h
+                     (search-input-file inputs "include/libudev.h")))
                 (substitute* "Makefile.inc"
                   (("\\$\\(prefix\\)/usr") "$(prefix)")
                   ;; Do not save timestamp to avoid gzip "timestamp
                   ;; out-of-range" warnings.
                   (("gzip -9") "gzip -9n"))
                 (substitute* '("kpartx/Makefile" "libmultipath/Makefile")
-                 (("/usr/include/libdevmapper.h")
+                  (("/usr/include/libdevmapper.h") libdevmapper.h)
-                  (string-append lvm2 "/include/libdevmapper.h"))
+                  (("/usr/include/libudev.h") libudev.h)))))
-                 (("/usr/include/libudev.h")
-                  (string-append udev "/include/libudev.h")))
-               #t)))
           (add-after 'unpack 'fix-maybe-uninitialized-variable
             (lambda _
               ;; This variable gets initialized later if needed, but GCC 7
@@ -5258,16 +5255,14 @@ arrays when needed.")
               ;; https://www.redhat.com/archives/dm-devel/2020-March/msg00137.html
               (substitute* "libmultipath/structs_vec.c"
                 (("bool is_queueing;")
-                "bool is_queueing = false;"))
+                 "bool is_queueing = false;"))))
-             #t))
           (add-after 'unpack 'fix-linking-tests
             (lambda _
               ;; Add missing linker flag for -lmpathcmd.  This should be fixed
               ;; for versions > 0.8.4.
               (substitute* "tests/Makefile"
                 (("-lmultipath -lcmocka")
-                "-lmultipath -L$(mpathcmddir) -lmpathcmd -lcmocka"))
+                 "-lmultipath -L$(mpathcmddir) -lmpathcmd -lcmocka"))))
-             #t))
           (add-after 'unpack 'skip-failing-tests
             (lambda _
               ;; This test and the module's setup() test an arbitrary block
@@ -5278,20 +5273,19 @@ arrays when needed.")
               ;; The above triggers -Werror=unused-function.  Ignore it.
               (substitute* "tests/Makefile"
                 (("CFLAGS \\+= " match)
-                (string-append match "-Wno-error=unused-function ")))
+                 (string-append match "-Wno-error=unused-function ")))))
-             #t))
           (delete 'configure))))        ;no configure script
     (native-inputs
      (list perl pkg-config valgrind
            ;; For tests.
            cmocka))
     (inputs
-     `(("json-c" ,json-c)
+     (list json-c
-       ("libaio" ,libaio)
+           libaio
-       ("liburcu" ,liburcu)
+           liburcu
-       ("lvm2" ,lvm2)
+           lvm2
-       ("readline" ,readline)
+           readline
-       ("udev" ,eudev)))
+           eudev))
     (home-page "http://christophe.varoqui.free.fr/")
     (synopsis "Access block devices through multiple paths")
     (description