www/librewolf: fix build on powerpc64

/wrkdirs/usr/ports/www/librewolf/work/librewolf-117.0-1/third_party/highway/hwy/ops/ppc_vsx-inl.h:3193:41: error: use of undeclared identifier 'vec_cipher_be'

return BitCast(du8, detail::CipherVec{vec_cipher_be(
                                      ^