Tensilica iss provides support for applications running in freestanding
environment through SIMCALL command. It is used by Tensilica libc to
access argc/argv, for file I/O, etc.

Note that simcalls that accept buffer addresses expect virtual addresses.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>