Fix JavaScriptCore ftbfs on mips64(el)

Task-number: QTBUG-33187
Change-Id: Iaebca6f5095e16c0316549c8a548cfc0a447faf3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
use private linkage where possible

Change-Id: I3c0a1ae83615120f9a0cf8202d4facf915decde2
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>