[Visualizers] Fix Optional visualizer.

[curdeius]

Summary

As discussed in https://reviews.llvm.org/D118105#3268773, OptionalStorage has been changed in commit https://github.com/llvm/llvm-project/commit/fb9730575086b3c2ba38a1aabf3106b01339888b, but the visualizer still tries to use old members.

[RKSimon]

LGTM - cheers

[curdeius]

@RKSimon, do you happen to know if there is a way to test NatVis? Not even testing what it shows, but just that it won't error out?

llvm/utils/LLVMVisualizers/llvm.natvis

<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
   </Type>
 
   <Type Name="llvm::Triple">
     <DisplayString>{Data}</DisplayString>
   </Type>
   
   <Type Name="llvm::Optional&lt;*&gt;">
     <DisplayString Condition="!Storage.hasVal">None</DisplayString>
-    <DisplayString Condition="Storage.hasVal">{*(($T1 *)(unsigned char *)Storage.storage.buffer)}</DisplayString>
+    <DisplayString Condition="Storage.hasVal">{Storage.value}</DisplayString>
     <Expand>
-      <Item Name="[underlying]" Condition="Storage.hasVal">*(($T1 *)(unsigned char *)Storage.storage.buffer)</Item>
+      <Item Name="[underlying]" Condition="Storage.hasVal">Storage.value</Item>
     </Expand>
   </Type>
 
   <Type Name="llvm::Expected&lt;*&gt;">
     <DisplayString Condition="HasError">Error</DisplayString>
     <DisplayString Condition="!HasError">{*((storage_type *)TStorage.buffer)}</DisplayString>
     <Expand>
       <Item Name="[value]" Condition="!HasError">*((storage_type *)TStorage.buffer)</Item>