When the expected ROM overhead of a function is bigger than the actual function,
it is better to provide the function as static inline function in the header.
Added `event_wait_multi()` that takes an array of event queues rather than
a single event queues. The queue with the lowest index will have the highest
priority.
Unstructured static initializer like { 0 } lead to compilation errors on ESP8266, MSP430 and MIPS. Error messages are:
error: (near initialization for 'queue.event_list') [-Werror=missing-braces]
error: (near initialization for 'queue.waiter') [-Werror=missing-field-initializers]
This change fixes the compilation problem.