Expand target and sources before calling Builder#create_build_target

lib/rscons/builders/program.rb

@@ -41,7 +41,7 @@ module Rscons
       def create_build_target(options)
         env, target, vars = options.values_at(:env, :target, :vars)
         my_options = options.dup
-        unless env.expand_varref(target, vars) =~ /\./
+        unless target["."]
           my_options[:target] += env.expand_varref("${PROGSUFFIX}", vars)
         end
         super(my_options)