Moved the architecture and compiler dependent atomic implementations to to core/internal/atomic.d.
core.atomic and stdc.stdatomic now uses the internal atomic implemenation instead in order to use compiler intrinsics.
Especially stdatomic now uses more intrinsics when using LDC in order to get better code generation.
Moved the architecture and compiler dependent atomic implementations to to core/internal/atomic.d. core.atomic and stdc.stdatomic now uses the internal atomic implemenation instead in order to use compiler intrinsics.
Especially stdatomic now uses more intrinsics when using LDC in order to get better code generation.