[ruby/prism] Make sure Init_prism is visible for extension

https://github.com/ruby/prism/commit/4601d3adfd

prism/extension.c

@@ -1103,7 +1103,7 @@ parse_file_failure_p(int argc, VALUE *argv, VALUE self) {
 /**
  * The init function that Ruby calls when loading this extension.
  */
-PRISM_EXPORTED_FUNCTION void
+RUBY_FUNC_EXPORTED void
 Init_prism(void) {
     // Make sure that the prism library version matches the expected version.
     // Otherwise something was compiled incorrectly.

prism/extension.h

@@ -14,6 +14,6 @@ VALUE pm_integer_new(const pm_integer_t *integer);
 
 void Init_prism_api_node(void);
 void Init_prism_pack(void);
-PRISM_EXPORTED_FUNCTION void Init_prism(void);
+RUBY_FUNC_EXPORTED void Init_prism(void);
 
 #endif