signal: change sig_waitTimeoutSignal() to accept custom timeout hook

signal: change sig_waitTimeoutSignal() to accept custom timeout hook

Change sig_waitTimeoutSignal() to accept a function hook to be called
when the timeout expires, instead of always using the default timeout
callback.

This makes possible to specify custom timeout actions, i.e. changing the
state of other dependent or derived objects (e.g., events).

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4768 38d2e660-2303-0410-9eaa-f027e97ec537