Make HostFiles arch independent

Signed-off-by: Luca BRUNO <lucab@debian.org>
Remove ARM specific README

Instructions for building and using the ARM port are the same as
normal ARM.

Signed-off-by: Luca Bruno <lucab@debian.org>
Provide per-arch FunctionMonitor plugins

Split the FunctionMonitor implementation in arch-specific parts, keeping
a common interface.

Signed-off-by: Luca Bruno <lucab@debian.org>