doc: include/getopt.h: remove comments confusing Sphinx

The Sphinx documentation build process cannot handle the interspersed
'private:' and 'public:' comments. Remove them.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/include/getopt.h b/include/getopt.h
index 8645082..0cf7ee8 100644
--- a/include/getopt.h
+++ b/include/getopt.h
@@ -20,11 +20,9 @@
 	 * parsed all of @argv, then @index will equal @argc.
 	 */
 	int index;
-	/* private: */
 	/** @arg_index: Index within the current argument */
 	int arg_index;
 	union {
-		/* public: */
 		/**
 		 * @opt: Option being parsed when an error occurs. @opt is only
 		 * valid when getopt() returns ``?`` or ``:``.
@@ -35,7 +33,6 @@
 		 * is only valid when getopt() returns an option character.
 		 */
 		char *arg;
-	/* private: */
 	};
 };