[clang] [-Wunsafe-buffer-usage] Fix false negatives of missing 2-param span ctors in constructor initializers (PR #113226)

[Ziqing Luo via cfe-commits]

ziqingluo-90 wrote:

Worth to mention that there could be "false positives" introduced to those std::span calls in C'tor initializers because the safe-pattern matching is syntactic only,  which doesn't know there can be "call stacks" involved in those recursive cases.

https://github.com/llvm/llvm-project/pull/113226