Fix C lexer w.r.t function declarations

These tokens were missing the specific regex match arguments, causing
duplicated output.

This fixes #277.

lib/rouge/lexers/c.rb

@@ -158,10 +158,10 @@ module Rouge
         )mx do |m|
           # TODO: do this better.
           recurse m[1]
-          token Name::Function
+          token Name::Function, m[2]
           recurse m[3]
           recurse m[4]
-          token Punctuation
+          token Punctuation, m[5]
           push :statement
         end