specify the type desired for some *SUFFIX variables when they are used

lib/rscons/builders/cc.rb

@@ -6,13 +6,14 @@ module Rscons
         'CFLAGS' => [],
         'CPPFLAGS' => [],
         'OBJSUFFIX' => '.o',
-        'CSUFFIX' => ['.c'],
+        'CSUFFIX' => '.c',
         'CCCOM' => ['$CC', '-c', '-o', '$TARGET', '$CPPFLAGS', '$CFLAGS', '$SOURCES']
       }
     end
 
     def self.produces?(env, target, source)
-      target =~ /#{env['OBJSUFFIX']}$/ and env['CSUFFIX'].find {|ext| source =~ /#{ext}$/}
+      (env['OBJSUFFIX', :array].find {|os| target =~ /#{os}$/} and
+       env['CSUFFIX', :array].find {|cs| source =~ /#{cs}$/})
     end
 
     def run(env, target, source)

lib/rscons/builders/program.rb

@@ -19,7 +19,7 @@ module Rscons
         if source =~ /#{env['OBJSUFFIX']}$/ or source =~ /#{env['LIBSUFFIX']}$/
           source
         else
-          o_file = env.stem(source) + env['OBJSUFFIX']
+          o_file = env.stem(source) + env['OBJSUFFIX', :string]
           builder_class = env.builders.values.find { |klass| klass.produces?(env, o_file, source) }
           if builder_class
             builder = builder_class.new