Make this more idiomatic

Library/Homebrew/extend/string.rb

@@ -55,9 +55,7 @@ module StringInreplaceExtension
 
   # Removes variable assignments completely.
   def remove_make_var! flags
-    # Next line is for Ruby 1.9.x compatibility
-    flags = [flags] unless flags.kind_of? Array
-    flags.each do |flag|
+    Array(flags).each do |flag|
       # Also remove trailing \n, if present.
       sub = gsub! Regexp.new("^#{flag}[ \\t]*=(.*)$\n?"), "", false
       opoo "inreplace: removing '#{flag}' failed" if sub.nil?