Define an API for executing very limited functions on application
processors in a multiprocessor system, along with an x86-only
implementation.
The normal iPXE runtime environment is effectively non-existent on
application processors. There is no ability to make firmware calls
(e.g. to write to a console), and there may be no stack space
available.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
