libphobos/ChangeLog:

2019-04-20  Iain Buclaw  <ibuclaw@gdcproject.org>

	PR d/89293
	* libdruntime/core/atomic.d (casImpl): Remove static assert for
	GNU_Have_Atomics, add static path to handle missing atomic support.
	(atomicLoad): Likewise.
	(atomicStore): Likewise.
	(atomicFence):  Likewise.
	(atomicMutexHandle, AtomicMutex): Declare types.
	(_getAtomicMutex): New function.
	(getAtomicMutex): Declare.

From-SVN: r270470