[clang] [Thread Safety Analysis] Fix a bug of context saving in alias-analysis (PR #178825)

[Ziqing Luo via cfe-commits]

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@@ -726,11 +726,10 @@ void VarMapBuilder::VisitCallExpr(const CallExpr *CE) {
       }
     }
 
-    if (VDec && Ctx.lookup(VDec)) {
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ziqingluo-90 wrote:

`VMap->clearDefinition` does check if the context contains `VDec`, so this check is redundant.

https://github.com/llvm/llvm-project/pull/178825