BlackBerry mkspecs: optimize linker flags

BlackBerry mkspecs: optimize linker flags

* relro makes some sections read-only before giving control to the
program;
* now resolves all symbols when the program is started and allows for
 the GOT being marked read-only to prevent it from being overwritten.

These settings have been used internally for device builds already.

Change-Id: I9f62fffe618c75748e2357d1686289c23c5dbee5
Reviewed-by: Greg Bentz <gbentz@rim.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>