[clang] [-Wunsafe-buffer-usage] Suppress warning for multi-dimensional constant arrays (PR #118249)

[via cfe-commits]

jkorous-apple wrote:

We want to suppress warnings for subscript operator on multi-dimensional constant size arrays (not `array[]`) only where the index used is constant and within bounds.
You changes some test cases where multi-dimensional pointers are accessed. For those the upper bound is unknown at compile time and we need to keep the warning.

https://github.com/llvm/llvm-project/pull/118249