gc.c: fix argument types for st_foreach

* gc.c ({free,mark}_{method,const}_entry_i): fix argument types as
  st_data_t for st_foreach().

* gc.c (rgengc_unprotect_logging_exit_func_i): add third argument.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45864 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-05-08

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45865 b2dd03c8-39d4-4d8f-98ff-823fe69b080e