Bug#45288: pb2 returns a lot of compilation warnings on linux

Tag unused arguments.
      
Approved by: Marko (via IRC)

storage/innodb_plugin/os/os0file.c

@@ -1182,10 +1182,12 @@ UNIV_INTERN
 void
 os_file_set_nocache(
 /*================*/
-	int		fd,		/*!< in: file descriptor to alter */
-	const char*	file_name,	/*!< in: file name, used in the
-					diagnostic message */
-	const char*	operation_name)	/*!< in: "open" or "create"; used in the
+	int		fd		/*!< in: file descriptor to alter */
+	__attribute__((unused)),
+	const char*	file_name	/*!< in: used in the diagnostic message */
+	__attribute__((unused)),
+	const char*	operation_name __attribute__((unused)))
+					/*!< in: "open" or "create"; used in the
 					diagnostic message */
 {
 	/* some versions of Solaris may not have DIRECTIO_ON */