lttng-ust: Workaround for gcc-cross issue

:Release Notes:
Workaround for issue in OpenEmbedded gcc-cross package for GCC 4.7.2
compiler that affects lttng-ust.

:Detailed Notes:
Declare symbols __start___tracepoints_ptrs and __stop___tracepoints_ptrs
as hidden only rather than hidden and weak. This works around an as of
yet undiagnosed issue with the OpenEmbedded patchset for GCC 4.7.2.

:Testing Performed:
Confirmed that pmtrace_bundle tracepoints function with this patch
using current toolchain.

:QA Notes:
BAT - PASS
MiniBAT - PASS
No Regressions
QA validation for this change - PASS

:Issues Addressed:
[BHV-2914] lttng traces for palm bundle not working correctly
[BHV-7781] CCC: lttng-ust=v2.2.0-0webos1 (workaround gcc-cross issue)

Open-webOS-DCO-1.0-Signed-off-by: Martin Unsal <martin.unsal@lge.com>
Change-Id: I49f829ae0cbf53947ce2c21b77655632b995626b
Reviewed-on: https://g2g.palm.com/5645
Reviewed-by: DCO Verification
Tested-by: Susan Montooth <susan.montooth@lge.com>
Build: Susan Montooth <susan.montooth@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>