The mutex implementation needs a different implementation once support
for threading lands. This implementation just moves code to the
internal/task package to centralize these algorithms.
This actually simplifies the code and avoids a heap allocation in the
call to Wait. Instead, it uses the Data field of the task to store
information on whether a task was signalled early.
Ayke van Laethem
Federico G. Schwindt
Jaden Weiss