LibX86: Add CMPXCHG8B, RDRAND and RDSEED

With this we can run following script with no errors:
```sh
for /usr/lib/*.so {
    disasm "$it" > /dev/zero
}
```

2 files changed, 8 insertions, 0 deletions

diff --git a/Userland/DevTools/UserspaceEmulator/SoftCPU.cpp b/Userland/DevTools/UserspaceEmulator/SoftCPU.cpp
index 4f8eb02acc..f0bd530026 100644
--- a/Userland/DevTools/UserspaceEmulator/SoftCPU.cpp
+++ b/Userland/DevTools/UserspaceEmulator/SoftCPU.cpp
@@ -2902,6 +2902,10 @@ FPU_INSTRUCTION(MOVD_rm32_mm2);
 FPU_INSTRUCTION(MOVQ_rm64_mm2); // long mode
 FPU_INSTRUCTION(EMMS);
 
+void SoftCPU::CMPXCHG8B_m64(X86::Instruction const&) { TODO_INSN(); }
+void SoftCPU::RDRAND_reg(X86::Instruction const&) { TODO_INSN(); }
+void SoftCPU::RDSEED_reg(X86::Instruction const&) { TODO_INSN(); }
+
 VPU_INSTRUCTION(PREFETCHTNTA);
 VPU_INSTRUCTION(PREFETCHT0);
 VPU_INSTRUCTION(PREFETCHT1);
diff --git a/Userland/DevTools/UserspaceEmulator/SoftCPU.h b/Userland/DevTools/UserspaceEmulator/SoftCPU.h
index e8540cdae3..0a0a600754 100644
--- a/Userland/DevTools/UserspaceEmulator/SoftCPU.h
+++ b/Userland/DevTools/UserspaceEmulator/SoftCPU.h
@@ -1109,6 +1109,10 @@ private:
     virtual void MOVQ_rm64_mm2(const X86::Instruction&) override; // long mode
     virtual void EMMS(const X86::Instruction&) override;
 
+    virtual void CMPXCHG8B_m64(X86::Instruction const&) override;
+    virtual void RDRAND_reg(X86::Instruction const&) override;
+    virtual void RDSEED_reg(X86::Instruction const&) override;
+
     virtual void PREFETCHTNTA(X86::Instruction const&) override;
     virtual void PREFETCHT0(X86::Instruction const&) override;
     virtual void PREFETCHT1(X86::Instruction const&) override;