Subzero: Reduce the amount of #ifdef'd code.

Try to make most #ifdef'd code be compiled under all configurations,
to catch code rot earlier.  When #ifdef code is required, try to use
it only to guard trivial code like "return;".

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1197863003
35 files changed