Make use of BSS more explicit in global initializers (vs a local .comm).

Make use of BSS more explicit in global initializers (vs a local .comm).

This reduces the number of conditionals, and will more closely reflect
the structure of the ELF writer's version of the same thing.
Without fdata-sections, the ELF writer version will have to batch all
initializers of a certain type so that they can be contiguous on the file
and the overall alignment can be determined.

A downside of this is that, .s files will be different from llc's output.
The spec .o and executables are identical before/after the change.

BUG=none
R=kschimpf@google.com, stichnot@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=fed97afff11dfdf934a8d3f980651804ddd93586

[jvoung (off chromium), 2015-01-24 00:00:19]

jvoung@chromium.org changed reviewers:
+ kschimpf@chromium.org, stichnot@chromium.org

[Jim Stichnoth, 2015-01-24 17:04:00]

lgtm

[Karl, 2015-01-24 17:07:23]

kschimpf@google.com changed reviewers:
+ kschimpf@google.com

[Karl, 2015-01-24 17:07:24]

lgtm

[jvoung (off chromium), 2015-01-25 18:46:06]

Committed patchset #2 (id:20001) manually as
fed97afff11dfdf934a8d3f980651804ddd93586 (presubmit successful).