Instrumented libraries: fix pulseaudio on Trusty, again.

Instrumented libraries: fix pulseaudio on Trusty, again.

libpulsecommon has moved to <libdir>/pulseaudio/. Update RPATH so that
instrumented libpulsecommon could be picked up from the new location.

This is not ideal as RPATH in libpulsecommon itself is still wrong. If that
bites us, we'll need to either fix it separately or just move libpulsecommon to
<libdir>. The latter approach would also help with other packages that might
depend on it.

BUG=414189
TBR=glider@chromium.org
NOTRY=true

Committed: https://crrev.com/b86366972c7f6b956bc56528287b7d1ab7ed0b71
Cr-Commit-Position: refs/heads/master@{#303830}

[earthdok, 2014-11-12 14:18:27]

The CQ bit was checked by earthdok@chromium.org

[commit-bot: I haz the power, 2014-11-12 14:19:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/719083002/1

[commit-bot: I haz the power, 2014-11-12 14:19:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-12 14:20:24]

Patchset 1 (id:??) landed as
https://crrev.com/b86366972c7f6b956bc56528287b7d1ab7ed0b71
Cr-Commit-Position: refs/heads/master@{#303830}