[clang] [Clang] Drop workaround for old gcc versions (PR #78803)

[via cfe-commits]

================
@@ -13637,11 +13636,10 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
     auto TransformFunctionProtoTypeLoc =
         [this](TypeLocBuilder &TLB, FunctionProtoTypeLoc FPTL) -> QualType {
       SmallVector<QualType, 4> ExceptionStorage;
-      TreeTransform *This = this; // Work around gcc.gnu.org/PR56135.
       return this->TransformFunctionProtoType(
           TLB, FPTL, nullptr, Qualifiers(),
           [&](FunctionProtoType::ExceptionSpecInfo &ESI, bool &Changed) {
-            return This->TransformExceptionSpec(FPTL.getBeginLoc(), ESI,
+            return this->TransformExceptionSpec(FPTL.getBeginLoc(), ESI,
----------------
cor3ntin wrote:

```suggestion
            return TransformExceptionSpec(FPTL.getBeginLoc(), ESI,
```

https://github.com/llvm/llvm-project/pull/78803