- Add function "mysqld_real_path" which is needed if the mysqld_path is a symlink or a script(like libtool) that executes the real mysqld.
- Add new variable mysqld_real_path
- Use mysqld_real_path from fill_instance_version


server-tools/instance-manager/instance_options.cc:
  Add function "mysqld_real_path" which is needed if the mysqld_path is a symlink or a script(like libtool) that executes the real mysqld.
  Add new variable mysqld_real_path
  Use mysqld_real_path from fill_instance_version
server-tools/instance-manager/instance_options.h:
  Add new variable "mysqld_real_path"