This only works 64->64, 32->32, and 64->32. We shouldn't have a
need for 32->64. It will also currently not work if the crash service
is running on Wow64 itself (that is, 32->32, but on an x64 OS). We
should also be able to avoid needing that.
Primarily, this change templatizes the winternl.h process structure
types on word size, so the PEB can be read in a foreign bitsize process.
This also happens to resolve using void* as pointer values into foreign
processes, as they're now all either DWORD or DWORD64 depending on which
traits class is used.
R=mark@chromium.org
BUG=crashpad:1
Review URL: https://codereview.chromium.org/981393003
