[clang] [clang] Avoid -Wshadow warning when init-capture named same as class field (PR #74512)

[Shafik Yaghmour via cfe-commits]

================
@@ -179,3 +179,21 @@ void f() {
 #endif
 }
 }
+
+namespace GH71976 {
+struct A {
+  int b = 5;
+  int foo() {
+    return [b = b]() { return b; }();
----------------
shafik wrote:

```suggestion
    return [b = b]() { return b; }(); // no diagnostic, init-capture does not shadow b
```

https://github.com/llvm/llvm-project/pull/74512