The simulator defines PLATFORM_HOSTED, as RaaA will do (RaaA will not define SIMULATOR).
The new define is to (de-)select code to compile on hosted platforms generally.
Should be no functional change to targets or the simulator.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27019 a1c6a512-1295-4272-9138-f99709370657