darwin.file_cmds: add libmd for install (#354897)

pkgs/os-specific/darwin/apple-source-releases/file_cmds/meson.build.in

···
 
 bzip2 = dependency('bzip2')
 xz = dependency('liblzma')
+libmd = dependency('libmd')
 libxo = dependency('libxo')
 zlib = dependency('zlib')
 
···
 
 executable(
     'install-bin', # Meson reserves the name “install”, so use a different name and rename in install phase.
-    dependencies : [ copyfile ],
+    dependencies : [ copyfile, libmd ],
     install : true,
     sources: [
         'install/xinstall.c',

pkgs/os-specific/darwin/apple-source-releases/file_cmds/package.nix

···
   bzip2,
   copyfile,
   less,
+  libmd,
   libutil,
   libxo,
   mkAppleDerivation,
···
   buildInputs = [
     bzip2
     copyfile
+    libmd
     libutil
     libxo
     removefile