[clang] [clang-repl] Fix Lexical DeclContext Mismatch Inside Namespaces (PR #206807)

[via cfe-commits]

yashg16422-design wrote:

A regression test for this fix would normally go in clang/test/Interpreter/fail.cpp. However, adding one is currently blocked by a pre-existing infinite loop in clang-repl's parser error recovery (Issue #206808, related to PR #127569 which already has an LGTM from @vgvassilev). Once #127569 lands, a test of the form:
// RUN: not --crash clang-repl "namespace v1 { int x = }" 2>&1 | FileCheck %s
// CHECK: error: expected expression
can be added. Requesting reviewer guidance on whether to block this PR on that fix or proceed without the test now.

https://github.com/llvm/llvm-project/pull/206807