Always define HAVE_VA_ARGS_MACRO on TruffleRuby

Author: eregon

lib/cext/include/ruby/internal/config.h

@@ -56,6 +56,11 @@
 #  define HAVE_VA_ARGS_MACRO
 # else
 #  /* NG, not known. */
+// Always define HAVE_VA_ARGS_MACRO on TruffleRuby, as it leads to cleaner macros and more optimizations:
+// clang++ on macOS Ventura has __cplusplus defined as 199711 but it supports newer standards like c++11
+#ifdef TRUFFLERUBY
+#define HAVE_VA_ARGS_MACRO
+#endif
 # endif
 #endif