[libc++] basic_string::resize_and_overwrite: Adopt LWG3645 (Not voted in yet)

Adopt LWG3645, which fixes the value categories of basic_string::resize_and_overwrite
https://timsong-cpp.github.io/lwg-issues/3645

Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D116815

GitOrigin-RevId: 48224475222d14e6f661d649f4363dcc197cc7ef
3 files changed