[GlobalISel] Fix typo with missed override specifier

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338689 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Alexander Ivchenko

lib/Target/Mips/MipsCallLowering.h

@@ -51,7 +51,7 @@ class MipsCallLowering : public CallLowering {
   MipsCallLowering(const MipsTargetLowering &TLI);
 
   bool lowerReturn(MachineIRBuilder &MIRBuilder, const Value *Val,
-                   ArrayRef<unsigned> VRegs) const;
+                   ArrayRef<unsigned> VRegs) const override;
 
   bool lowerFormalArguments(MachineIRBuilder &MIRBuilder, const Function &F,
                             ArrayRef<unsigned> VRegs) const override;