struct plugin_api *rb is declared in PLUGIN_HEADER, and pointed to by
__header.api
the loader uses this pointer to initialize rb before calling entry_point
entry_point is no longer passed a pointer to the plugin API
all plugins, and pluginlib functions, are modified to refer to the
global rb
pluginlib functions which only served to copy the API pointer are
removed
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19776 a1c6a512-1295-4272-9138-f99709370657
