[clang] [Clang][Parser] Make 'T...[N]' within a function parameter a valid pack expansion prior to C++2c (PR #116332)

[via cfe-commits]

cor3ntin wrote:

> Are we finding that we have uses of this? 

Unlikely
 - Not supported by GCC / MSVC
 - Really weird way to spell T*
 - My research did not find any uses

All of which factored into WG21 introducing this breaking change

https://github.com/llvm/llvm-project/pull/116332