[lld] [LLD] Improve linker script handing in LLD (PR #106334)

[Hongyu Chen via llvm-commits]

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@@ -74,6 +75,111 @@ struct ExprValue {
 // Later, we evaluate the expression by calling the function.
 using Expr = std::function<ExprValue()>;
 
+class ScriptExpr {
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yugier wrote:

Updated `ScriptExpr` to `Expr` and added some comments but not sure if they are good ones. 

https://github.com/llvm/llvm-project/pull/106334