Int128.multipliedFullWidth fails to account for an overflow case, which lead `Duration.components` trapping when the duration is a multiple of 512s.
rdar://96362510
There is still an open radar for the author to consider deleting
the test or reimagining it somehow:
rdar:94451729 (Swift CI: Concurrency/Runtime/clock.swift failed
despite increased timeout)
* Ensure clocks properly respect leeways and use raw time for calculations for continuous clocks
* slurp up time calcualtions to inline forms
* ensure the tolerance codepaths get tested as well
* Use task local storage for task sources in leeway based calculations
* use comparison assertions for leeway based calculations
* Whitespace cleanup
* Use the CLOCK_MONOTONIC value for linux to be compatible with linux scheduling for dispatch
* remove incorrect paren in macro check for OpenBSD
* Address feedback and remove stray ;
