Fix format not a string literal security error in rb_raise

(cherry picked from commit 44273426d1)

amarok/src/mediadevice/daap/mongrel/http11/http11.c

@@ -46,7 +46,7 @@ static VALUE global_port_80;
 #define DEF_MAX_LENGTH(N,length) const size_t MAX_##N##_LENGTH = length; const char *MAX_##N##_LENGTH_ERR = "HTTP element " # N  " is longer than the " # length " allowed length."
 
 /** Validates the max length of given input and throws an HttpParserError exception if over. */
-#define VALIDATE_MAX_LENGTH(len, N) if(len > MAX_##N##_LENGTH) { rb_raise(eHttpParserError, MAX_##N##_LENGTH_ERR); }
+#define VALIDATE_MAX_LENGTH(len, N) if(len > MAX_##N##_LENGTH) { rb_raise(eHttpParserError, "%s", MAX_##N##_LENGTH_ERR); }
 
 /** Defines global strings in the init method. */
 #define DEF_GLOBAL(N, val)   global_##N = rb_obj_freeze(rb_str_new2(val)); rb_global_variable(&global_##N)