Add configure/CMake flags for conditionally building subzero targets.

Add configure/CMake flags for conditionally building subzero targets.

Enable/disable X8632 vs ARM32, etc. so that a
target-specific binary doesn't grow much as we add more
targets.

Also update LLVM component revisions for:
LLVM change: https://codereview.chromium.org/1084753002/

8284e69: (jvoung@chromium.org) Add some configure/CMake options for enabling/disabling Subzero targets.

Later Subzero change: https://codereview.chromium.org/1075363002/

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4076
R=stichnot@chromium.org

Committed: https://chromium.googlesource.com/native_client/src/native_client/+/0b3aba109505d26c90fc21d2cb01374d4ad940fc

[jvoung (off chromium), 2015-04-17 21:08:08]

jvoung@chromium.org changed reviewers:
+ dschuff@chromium.org, jfb@chromium.org, mtrofin@chromium.org,
stichnot@chromium.org

[Jim Stichnoth, 2015-04-17 22:28:44]

lgtm

https://codereview.chromium.org/1082953002/diff/1/pnacl/build.sh
File pnacl/build.sh (right):

https://codereview.chromium.org/1082953002/diff/1/pnacl/build.sh#newcode307
pnacl/build.sh:307: local subzero_targets=""
Since we all love writing compact bash scripts, how about this instead of the
case statement:

declare -A targets=( [i686]=x86 [x86_64]=x86 [armv7]=arm \
                     [universal]=x86,arm )
declare -A subzero_targets=( [i686]=X8632 [x86_64]=X8664 [armv7]=ARM32 \
                             [universal]=X8632,ARM32 )

And below:
  --enable-targets=${targets[$arch]} \
  --enable-subzero-targets=${subzero_targets[$arch]} \

You're welcome.

[jvoung (off chromium), 2015-04-21 23:46:06]

Committed patchset #2 (id:20001) manually as
0b3aba109505d26c90fc21d2cb01374d4ad940fc (presubmit successful).