aardvark_shell_utils: add conflict with coreutils

Closes Homebrew/homebrew#42767.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Formula/aardvark_shell_utils.rb

@@ -4,8 +4,11 @@ class AardvarkShellUtils < Formula
   url "http://downloads.laffeycomputer.com/current_builds/shellutils/aardvark_shell_utils-1.0.tar.gz"
   sha256 "aa2b83d9eea416aa31dd1ce9b04054be1a504e60e46426225543476c0ebc3f67"
 
+  conflicts_with "coreutils", :because => "both install `realpath` binaries"
+
   def install
-    system "./configure", "--disable-debug", "--disable-dependency-tracking",
+    system "./configure", "--disable-debug",
+                          "--disable-dependency-tracking",
                           "--prefix=#{prefix}",
                           "--mandir=#{man}"
     system "make"