misc: Get gem5 to build with Clang 8

Added missing overrides:
- src/mem/token_port.hh
- src/sim/power/mathexpr_powermodel.hh

Remove Unused static constants:
- src/arch/x86/process.cc

Related Issue: https://gem5.atlassian.net/projects/GEM5/issues/GEM5-534

Change-Id: Icc725e2522dcee919e299f4ea7a9f1773f5dfa4d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28947
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/x86/process.cc

@@ -67,32 +67,6 @@
 using namespace std;
 using namespace X86ISA;
 
-static const int ArgumentReg[] = {
-    INTREG_RDI,
-    INTREG_RSI,
-    INTREG_RDX,
-    // This argument register is r10 for syscalls and rcx for C.
-    INTREG_R10W,
-    // INTREG_RCX,
-    INTREG_R8W,
-    INTREG_R9W
-};
-
-static const int NumArgumentRegs M5_VAR_USED =
-    sizeof(ArgumentReg) / sizeof(const int);
-
-static const int ArgumentReg32[] = {
-    INTREG_EBX,
-    INTREG_ECX,
-    INTREG_EDX,
-    INTREG_ESI,
-    INTREG_EDI,
-    INTREG_EBP
-};
-
-static const int NumArgumentRegs32 M5_VAR_USED =
-    sizeof(ArgumentReg) / sizeof(const int);
-
 template class MultiLevelPageTable<LongModePTE<47, 39>,
                                    LongModePTE<38, 30>,
                                    LongModePTE<29, 21>,

src/mem/token_port.hh

@@ -94,7 +94,7 @@ class TokenSlavePort : public SlavePort
 
     std::deque<PacketPtr> respQueue;
 
-    void recvRespRetry();
+    void recvRespRetry() override;
 
   public:
     TokenSlavePort(const std::string& name, ClockedObject *owner,

src/sim/power/mathexpr_powermodel.hh

@@ -64,14 +64,14 @@ class MathExprPowerModel : public PowerModelState
      *
      * @return Power (Watts) consumed by this object (dynamic component)
      */
-    double getDynamicPower() const { return eval(dyn_expr); }
+    double getDynamicPower() const override { return eval(dyn_expr); }
 
     /**
      * Get the static power consumption.
      *
      * @return Power (Watts) consumed by this object (static component)
      */
-    double getStaticPower() const { return eval(st_expr); }
+    double getStaticPower() const override { return eval(st_expr); }
 
     /**
      * Get the value for a variable (maps to a stat)