Along with the nexe equivalents of pnacl-sz, also build the browser-integrated versions that can be dropped in as replacements.  Note that these are not exact replacements, as they likely support all targets.

In "make presubmit", instead build sandboxed translators in DEBUG=1 mode, so they can build in parallel with the assembler unit tests.

Add a "make bloat-sb" target that does the "make bloat" equivalent for the sandboxed translators.

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1746593002 .