X86: Add a bitfield to indicate whether or not an REX prefix was present.
X86: Add a bitfield to indicate whether or not an REX prefix was present.

--HG--
extra : convert_revision : 9c4802f6c6e4eaab36aac900e2c7576682cb0f33

cancro7/gem5,sobercoder/gem5,kaiyuanl/gem5,zlfben/gem5,TUD-OS/gem5-dtu,gedare/gem5,samueldotj/TeeRISC-Simulator,aclifton/cpeg853-gem5,qizenguf/MLC-STT,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,rallylee/gem5,markoshorro/gem5,HwisooSo/gemV-update,rjschof/gem5,samueldotj/TeeRISC-Simulator,gem5/gem5,gedare/gem5,Weil0ng/gem5,yb-kim/gemV,zlfben/gem5,briancoutinho0905/2dsampling,austinharris/gem5-riscv,gem5/gem5,KuroeKurose/gem5,gem5/gem5,samueldotj/TeeRISC-Simulator,yb-kim/gemV,rallylee/gem5,samueldotj/TeeRISC-Simulator,briancoutinho0905/2dsampling,qizenguf/MLC-STT,samueldotj/TeeRISC-Simulator,TUD-OS/gem5-dtu,cancro7/gem5,Weil0ng/gem5,qizenguf/MLC-STT,Weil0ng/gem5,qizenguf/MLC-STT,aclifton/cpeg853-gem5,HwisooSo/gemV-update,austinharris/gem5-riscv,aclifton/cpeg853-gem5,gem5/gem5,KuroeKurose/gem5,cancro7/gem5,yb-kim/gemV,gedare/gem5,KuroeKurose/gem5,joerocklin/gem5,austinharris/gem5-riscv,rjschof/gem5,zlfben/gem5,kaiyuanl/gem5,zlfben/gem5,Weil0ng/gem5,yb-kim/gemV,joerocklin/gem5,samueldotj/TeeRISC-Simulator,HwisooSo/gemV-update,cancro7/gem5,TUD-OS/gem5-dtu,samueldotj/TeeRISC-Simulator,gedare/gem5,joerocklin/gem5,aclifton/cpeg853-gem5,sobercoder/gem5,rjschof/gem5,markoshorro/gem5,HwisooSo/gemV-update,yb-kim/gemV,qizenguf/MLC-STT,rjschof/gem5,zlfben/gem5,qizenguf/MLC-STT,SanchayanMaity/gem5,gedare/gem5,aclifton/cpeg853-gem5,briancoutinho0905/2dsampling,Weil0ng/gem5,gedare/gem5,rjschof/gem5,joerocklin/gem5,kaiyuanl/gem5,gem5/gem5,rallylee/gem5,TUD-OS/gem5-dtu,joerocklin/gem5,powerjg/gem5-ci-test,SanchayanMaity/gem5,cancro7/gem5,austinharris/gem5-riscv,zlfben/gem5,powerjg/gem5-ci-test,yb-kim/gemV,briancoutinho0905/2dsampling,gem5/gem5,powerjg/gem5-ci-test,TUD-OS/gem5-dtu,sobercoder/gem5,markoshorro/gem5,rjschof/gem5,briancoutinho0905/2dsampling,KuroeKurose/gem5,aclifton/cpeg853-gem5,KuroeKurose/gem5,powerjg/gem5-ci-test,rallylee/gem5,KuroeKurose/gem5,cancro7/gem5,SanchayanMaity/gem5,SanchayanMaity/gem5,SanchayanMaity/gem5,yb-kim/gemV,joerocklin/gem5,yb-kim/gemV,sobercoder/gem5,markoshorro/gem5,rjschof/gem5,markoshorro/gem5,rallylee/gem5,HwisooSo/gemV-update,Weil0ng/gem5,joerocklin/gem5,SanchayanMaity/gem5,HwisooSo/gemV-update,sobercoder/gem5,qizenguf/MLC-STT,TUD-OS/gem5-dtu,HwisooSo/gemV-update,cancro7/gem5,powerjg/gem5-ci-test,austinharris/gem5-riscv,KuroeKurose/gem5,kaiyuanl/gem5,Weil0ng/gem5,markoshorro/gem5,austinharris/gem5-riscv,TUD-OS/gem5-dtu,markoshorro/gem5,SanchayanMaity/gem5,joerocklin/gem5,zlfben/gem5,rallylee/gem5,sobercoder/gem5,powerjg/gem5-ci-test,austinharris/gem5-riscv,kaiyuanl/gem5,gedare/gem5,kaiyuanl/gem5,briancoutinho0905/2dsampling,aclifton/cpeg853-gem5,kaiyuanl/gem5,sobercoder/gem5,rallylee/gem5,gem5/gem5