Fix some problems on ppc64le
Fix some problems on ppc64le

Altivec code assumed big-endian.

webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,randombit/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,randombit/botan,webmaster128/botan,webmaster128/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,randombit/botan,randombit/botan