powerpc: update mem barrier instructions

[bureddy]

   - added isync interface.
   - define ocoms_atomic_wmb() to lwsync as it is recommend over eieio
     on cache enabled storage.
    (http://www.ibm.com/developerworks/systems/articles/powerpc.html).

[mellanox-github]

Refer to this link for build results (access rights to CI server needed):
http://bgate.mellanox.com/job/gh-ompi-master-pr/658/

[bosilca]

Gotcha! The functions should not be named ocoms but opal. Bad bad C&P

[mellanox-github]

Refer to this link for build results (access rights to CI server needed):
http://bgate.mellanox.com/job/gh-ompi-master-pr/663/

Build Log
last 50 lines

GitHub pull request #664 of commit ed406b05cbddc40283593d69b178c67b1c4b0880, no merge conflicts.
Setting status of ed406b05cbddc40283593d69b178c67b1c4b0880 to PENDING with url http://bgate.mellanox.com:8888/jenkins/job/gh-ompi-master-pr/663/ and message: 'Build started, sha1 is merged'
Using conext: Mellanox
[EnvInject] - Loading node environment variables.
Building on master in workspace /var/lib/jenkins/jobs/gh-ompi-master-pr/workspace
Wiping out workspace first.
Cloning the remote Git repository
Cloning repository https://github.com/open-mpi/ompi
 > /usr/bin/git init /var/lib/jenkins/jobs/gh-ompi-master-pr/workspace # timeout=60
Fetching upstream changes from https://github.com/open-mpi/ompi
 > /usr/bin/git --version # timeout=60
using .gitcredentials to set credentials
 > /usr/bin/git config --local credential.helper store --file=/tmp/git8473309417074564755.credentials # timeout=60
 > /usr/bin/git -c core.askpass=true fetch --tags --progress https://github.com/open-mpi/ompi +refs/heads/*:refs/remotes/origin/* # timeout=60
 > /usr/bin/git config --local --remove-section credential # timeout=60
Build was aborted
Aborted by anonymous
[htmlpublisher] Archiving HTML reports...
[htmlpublisher] Archiving at BUILD level /var/lib/jenkins/jobs/gh-ompi-master-pr/workspace/cov_build to /var/lib/jenkins/jobs/gh-ompi-master-pr/builds/663/htmlreports/Coverity_Report
Setting commit status on GitHub for https://github.com/open-mpi/ompi/commit/4a094fa3951026d1f186001f2359d0bb9f1787f8
[BFA] Scanning build for known causes...
[BFA] No failure causes found
[BFA] Done. 0s
Setting status of ed406b05cbddc40283593d69b178c67b1c4b0880 to FAILURE with url http://bgate.mellanox.com:8888/jenkins/job/gh-ompi-master-pr/663/ and message: 'Build finished.'
Using conext: Mellanox

[bureddy]

sorry abt that :-) . fixed it

[hppritcha]

bot:retest

[hjelmn]

👍

[jsquyres]

@hjelmn and @bosilca talked about this with @bureddy in the room at the June 2015 dev meeting; this looks good.