Give option to use isCopyInstr to determine which MI is

treated as Copy instruction in MCP.

This is then used in AArch64 to remove copy instructions after taildup
ran in machine block placement

Differential Revision: https://reviews.llvm.org/D125335

Author: Adrian Tong

llvm/include/llvm/CodeGen/Passes.h

@@ -331,6 +331,8 @@ namespace llvm {
   /// machine instructions.
   extern char &MachineCopyPropagationID;
 
+  MachineFunctionPass *createMachineCopyPropagationPass(bool UseCopyInstr);
+
   /// PeepholeOptimizer - This pass performs peephole optimizations -
   /// like extension and comparison eliminations.
   extern char &PeepholeOptimizerID;