gnu: scilab: Fix the scilab build script.

* gnu/packages/maths.scm (scilab):
[arguments]<#:phases>: Reintroduce a manual patch for /bin/ls in phase
pre-build. This is necessary because the file is used when scilab
builds macros, even if it is discarded later.
[inputs]: Add coreutils-minimal.

Change-Id: I692fd6696273bfdce0e50b0f688a60e7dc289ce6
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/maths.scm

@@ -9966,6 +9966,7 @@ (define-public scilab
            autoconf-archive
            automake
            bison
+           coreutils-minimal
            eigen
            flex
            gfortran
@@ -10073,6 +10074,10 @@ (define-public scilab
                     (("PROGNAME.*") "\n")))))
             (add-before 'build 'pre-build
               (lambda* (#:key inputs #:allow-other-keys)
+                ;; Fix scilab script.
+                (substitute* "bin/scilab"
+                  (("/bin/ls")
+                   (search-input-file inputs "bin/ls")))
                 ;; Fix core.start.
                 (substitute* "modules/core/etc/core.start"
                   (("'SCI/modules")