Power 8 support, phase 5 

This commit adds support for the following instructions for doing
various arithmetic, bit transformation, cipher, count, logical,
and SHA operations.

  vpmsumb, vpmsumh, vpmsumw, vpmsumd, vpermxor, vcipher, vcipherlast,
  vncipher, vncipherlast, vsbox,
  vclzb, vclzw, vclzh, vclzd,
  vpopcntb, vpopcnth, vpopcntw, vpopcntd,
  vnand, vorc, veqv,
  vshasigmaw, vshasigmad,
  bcdadd, bcdsub

The following Iops were added to support the above instructions:
  Iop_BCDAdd, Iop_BCDSub, 
  Iop_PolynomialMulAdd8x16, Iop_PolynomialMulAdd16x8,
  Iop_PolynomialMulAdd32x4, Iop_PolynomialMulAdd64x2,
  Iop_CipherV128, Iop_CipherLV128, Iop_CipherSV128,
  Iop_NCipherV128, Iop_NCipherLV128,
  Iop_SHA512, Iop_SHA256, Iop_Clz64x2

The patch is for Bugzilla 325628


git-svn-id: svn://svn.valgrind.org/vex/trunk@2789 8f6e269a-dfd6-0310-a8e1-e2731360e62c