patch 8.0.1849: compiler warning for unused arguments, missing prototype

Problem:    compiler warning for unused arguments and missing prototype
Solution:   Add UNUSED.  Add static.
diff --git a/src/if_ruby.c b/src/if_ruby.c
index 5905424..eb79077 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -828,7 +828,7 @@
     }
 }
 
-VALUE rb_load_wrap(VALUE file_to_load)
+static VALUE rb_load_wrap(VALUE file_to_load)
 {
     rb_load(file_to_load, 0);
     return Qnil;