Move the bitcast instruction to the correct BB for DP emu

This change insert `i64 -> double` `BitCast` instruction
to the appropriate BB. Before this change, some `BitCast`
instructions can be inserted into incorrect BB, e.g. PHINode:
```
for.cond:
  %0 = call i64 @llvm.genx.GenISA.WaveShuffleIndex.i64(i64 %x, i32 %y, i32 0)
  br label %BB_01

...

BB_01:
  %1 = bitcast i64 %0 to double
  %2 = phi double [ %a, %if.then ], [ %b, %if.then1 ], [ %c, %if.then2 ], [ %1, %for.cond ]
```

With this change, we'll get:
```
for.cond:
  %0 = call i64 @llvm.genx.GenISA.WaveShuffleIndex.i64(i64 %x, i32 %y, i32 0)
  %1 = bitcast i64 %0 to double
  br label %BB_01

...

BB_01:
  %2 = phi double [ %a, %if.then ], [ %b, %if.then1 ], [ %c, %if.then2 ], [ %1, %for.cond ]
```

Author: matborzyszkowski

IGC/Compiler/Optimizer/PreCompiledFuncImport.cpp

@@ -223,6 +223,7 @@ void PreCompiledFuncImport::handleInstrTypeChange(Instruction* oldInst, Value* n
         // in preProcessDouble() function. All extra bitcast instruction are deleted by InstructionCombining pass.
         else
         {
+            builder.SetInsertPoint(oldInst);
             if (newVal->getType()->isIntegerTy(64))
             {
                 Value* newBitCast = builder.CreateBitCast(newVal, builder.getDoubleTy());