Add error globals to mark list so they don't move

JSON gem is referencing constants defined in Ruby then keeping a
reference as a global.  We need to register these globals so they stay
pinned.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67483 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/json/generator/generator.c

@@ -1344,6 +1344,8 @@ void Init_generator(void)
 
     eGeneratorError = rb_path2class("JSON::GeneratorError");
     eNestingError = rb_path2class("JSON::NestingError");
+    rb_gc_register_mark_object(eGeneratorError);
+    rb_gc_register_mark_object(eNestingError);
 
     cState = rb_define_class_under(mGenerator, "State", rb_cObject);
     rb_define_alloc_func(cState, cState_s_allocate);

ext/json/parser/parser.c

@@ -2091,6 +2091,8 @@ void Init_parser(void)
     cParser = rb_define_class_under(mExt, "Parser", rb_cObject);
     eParserError = rb_path2class("JSON::ParserError");
     eNestingError = rb_path2class("JSON::NestingError");
+    rb_gc_register_mark_object(eParserError);
+    rb_gc_register_mark_object(eNestingError);
     rb_define_alloc_func(cParser, cJSON_parser_s_allocate);
     rb_define_method(cParser, "initialize", cParser_initialize, -1);
     rb_define_method(cParser, "parse", cParser_parse, 0);