[include-cleaner] Handle StdInitializerListExprs

Per C++ standard, programs omitting the definition for initializer_list
is ill-formed, https://eel.is/c++draft/dcl.init.list#2.

Fixes https://github.com/llvm/llvm-project/issues/64198

Differential Revision: https://reviews.llvm.org/D156712

GitOrigin-RevId: 3736eaa6a0b8396e30978c768c02e43c821a8257
2 files changed