Fix normalization of old- and new-style options

When combining the set of old-style and new-style options, make sure
that the leading "--" is stripped.

Fixes displaying options in `brew options`, and the exotic case of
declaring options using the old syntax and then checking them with
`build.include?`

Library/Homebrew/cmd/options.rb

@@ -32,8 +32,7 @@ module Homebrew extend self
 
   def dump_options_for_formula f
     f.build.each do |k,v|
-      k.prepend "--" unless k.start_with? "--"
-      puts k
+      puts "--"+k
       puts "\t"+v
     end
   end

Library/Homebrew/formula.rb

@@ -58,7 +58,10 @@ class Formula
     @downloader = download_strategy.new(name, @active_spec)
 
     # Combine DSL `option` and `def options`
-    options.each {|o| self.class.build.add(o[0], o[1]) }
+    options.each do |opt, desc|
+      # make sure to strip "--" from the start of options
+      self.class.build.add opt[/--(.+)$/, 1], desc
+    end
   end
 
   def url;      @active_spec.url;     end