fix checking file suffixes

lib/rscons/monkey/string.rb

@@ -2,7 +2,7 @@ class String
   def has_suffix?(suffix)
     if suffix
       suffix = [suffix] if suffix.is_a?(String)
-      suffix.find {|s| self =~ /#{s}$/}
+      suffix.find {|s| self.end_with?(s)}
     end
   end