Bug 966596: Fix compilation error on Linux when USE_X32=1. r=kaie.
Bug 966596: Fix compilation error on Linux when USE_X32=1. r=kaie.

ekr/nss-old,ekr/nss-old,nmav/nss,nmav/nss,ekr/nss-old,nmav/nss,nmav/nss,ekr/nss-old,nmav/nss,ekr/nss-old,nmav/nss,ekr/nss-old,nmav/nss,ekr/nss-old