Omit textual emitConstPool in MINIMAL build.

Omit textual emitConstPool in MINIMAL build.

Noticed the "Note: Still used by emit IAS" and decided
to check if we can omit it. Saves about 3KB.

There's also the "Note: Still used by emit IAS" CFG
text header, but I haven't looked at that.

This would silently cripple the -filetype=asm or
-filetype=iasm in the MINIMAL build, but that isn't
supposed to be supported. Had to conditionalize some more
of the tests.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4080
R=stichnot@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=b5447a0488d8c33b5e2b35902b6865fc275ca6d1

[jvoung (off chromium), 2015-02-24 22:50:46]

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

[Jim Stichnoth, 2015-02-25 00:07:40]

LGTM.

All textual emission is expressly not supported in the MINIMAL mode, since the
minimal mode assumes there is no assembler step in the translation pipeline.

I think it should be fine to do the same thing for Cfg::emitTextHeader().

[jvoung (off chromium), 2015-02-25 00:57:31]

Committed patchset #2 (id:20001) manually as
b5447a0488d8c33b5e2b35902b6865fc275ca6d1 (presubmit successful).