Don't print error message when dev_tools_path fails to find tools

This message is either (a) never printed because the tools are
installed, or (b) printed every time this method is called.

See Homebrew/homebrew#16119.

This code shouldn't be responsible for UX anyway, so just remove it and
let other parts of Homebrew be responsible for failing or declaring that
they need the developer tools.

Library/Homebrew/macos.rb

@@ -50,10 +50,6 @@ module MacOS extend self
     elsif File.exist? "#{Xcode.prefix}/usr/bin/make"
       # cc stopped existing with Xcode 4.3, there are c89 and c99 options though
       Pathname.new "#{Xcode.prefix}/usr/bin"
-    else
-      # Since we are pretty unrelenting in finding Xcode no matter where
-      # it hides, we can now throw in the towel.
-      opoo "Could not locate developer tools. Consult `brew doctor`."
     end
   end