Avoid -Wgnu-zero-variadic-macro-arguments warning

* .../languages/ruby/lib/cext/include/truffleruby/truffleruby.h:48:59:
warning: token pasting of ',' and __VA_ARGS__ is a GNU extension
[-Wgnu-zero-variadic-macro-arguments]
  rb_exc_raise(rb_exc_new_str(EXCEPTION, rb_sprintf(FORMAT, ##__VA_ARGS__)))
                                                          ^

Author: eregon

lib/cext/include/truffleruby/truffleruby.h

@@ -44,8 +44,8 @@ typedef void* (gvl_call)(void *);
 
 // Exceptions
 
-#define rb_raise(EXCEPTION, FORMAT, ...) \
-  rb_exc_raise(rb_exc_new_str(EXCEPTION, rb_sprintf(FORMAT, ##__VA_ARGS__)))
+#define rb_raise(EXCEPTION, ...) \
+  rb_exc_raise(rb_exc_new_str(EXCEPTION, rb_sprintf(__VA_ARGS__)))
 
 // Macros for rb_funcall(). As written they currently only work on Sulong.
 //