Removes the bitness-specific targets in favour of pulling binaries from
the other build directory. This is to avoid the added complexity of
duplicating all the targets for the x86 in x64 build.
Overall, mostly templatizing more functions to support the
wow64-flavoured structures. The only additional functionality required
is reading the x86 TEB that's chained from the x64 TEB when running
as WOW64.
The crashing child test was switched to a manual CreateProcess because
it needs to launch a binary other than itself.
R=mark@chromium.org
BUG=crashpad:50
Review URL: https://codereview.chromium.org/1349313003 .
