doing so. Changed the behaviour in case a driver is already loaded: Since the
library cannot know if this driver was linked statically or loaded
dynamically, an already installed driver is considered an error. It must be
removed before calling tgi_load_driver.
git-svn-id: svn://svn.cc65.org/cc65/trunk@5790 b7a2c559-68d2-44c3-8de9-860c34a00d81