This is a follow up patch to r349138.
This patch makes a AddressSpaceView a type declaration in the
allocator parameters used by SizeClassAllocator64. For ASan, LSan, and
the unit tests the AP64 declarations have been made templated so that
AddressSpaceView can be changed at compile time. For the other
sanitizers we just hard-code LocalAddressSpaceView because we have no
plans to use these allocators in an out-of-process manner.
rdar://problem/45284065