hw: use reliable start message in run env

Previously for determining wether boot-up succeeded or not, we looked
for a message that is switched off in release mode. Now the kernel
provides a reliable message as soon as initialization is done.
noux: make RM replay less noisy in release mode

As the message "replay: missing dataspace info for ..." occurs multiple times
on every fork, it slows down at least noux_tool_chain_auto with hw_arndale
about 10 seconds. To avoid this overhead in release mode I've turned it into a
warning rather than an error.
hw: combine end signals of processor broadcasts

We can reduce signalling overhead if we submit only one end signal as soon as
all processors finished the requested operation.