[clang] [-Wunterminated-string-initialization] Handle C string literals ending with explicit '\0' (PR #143487)

[Tom Weaver via cfe-commits]

TomWeaver18 wrote:

My apologies but I've had to revert this change to get the build bot green again.

Reverted in 30de98c283f5795dc10cc1c754d87f46a61d15ac

https://github.com/llvm/llvm-project/pull/143487