Add heap reference size to the checks in arch_test

As we will potentially make heap references larger than 32b on 64b
systems at some point, add a constant to the .h files that describes
what the current assembly implementation assumes about the size of
heap references, and check whether that agrees with sizeof.

Change-Id: I75ffd7e2b59891ec36977fd831a8d5faac69c76d
6 files changed