[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:

> This overlaps with #91991 which should probably be landed in its entirety. (It looks like it's about attributes but in fact it isn't. It's about finding _all_ gadgets in all those new places.) I think that patch was almost ready and it was a matter of considering my fix in [#91991 (comment)](https://github.com/llvm/llvm-project/pull/91991#discussion_r1643433741)

yeah, you are right.  Let's hang out in that PR then.

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