gnu: perl: Use ‘search-input-file’ to find ‘bin/pwd’

A recent change makes the ‘perl’ package explicitly reference input
“coreutils” or “coreutils-minimal” by label in the ‘setup-configure’ phase
but the ‘perl-boot0’ package, which uses ‘%boot0-inputs’ as its input list,
doesn’t have such input on non-x86-linux systems. This causes the build of
‘perl-boot0’ to fail on those systems.

Therefore use ‘search-input-file’ to find ‘bin/pwd’ and avoid referencing
the input label.

* gnu/packages/perl.scm (perl)[arguments]<#:phases>: Use
‘search-input-file’ to find ‘bin/pwd’.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/packages/perl.scm

@@ -124,18 +124,16 @@ (define-public perl
        (modify-phases %standard-phases
          (add-before 'configure 'setup-configure
            (lambda* (#:key inputs #:allow-other-keys)
-             (let ((coreutils (or (assoc-ref inputs "coreutils-minimal")
-                                  (assoc-ref inputs "coreutils"))))
              ;; Use the right path for `pwd'.
              (substitute* "dist/PathTools/Cwd.pm"
                (("'/bin/pwd'")
-                  (string-append "'" coreutils "/bin/pwd'")))
+                (string-append "'" (search-input-file inputs "bin/pwd") "'")))
 
              ;; Build in GNU89 mode to tolerate C++-style comment in libc's
              ;; <bits/string3.h>.
              (substitute* "cflags.SH"
                (("-std=c89")
-                  "-std=gnu89")))))
+                "-std=gnu89"))))
          ,@(if (%current-target-system)
                `((add-after 'unpack 'unpack-cross
                    (lambda* (#:key native-inputs inputs #:allow-other-keys)