[compiler-rt] [libc] [mlir] [llvm] [clang] [clang-tools-extra] [flang] [mlir][Linalg] Support dynamic shapes in `lower_pack` transform (PR #76003)

[via cfe-commits]

srcarroll wrote:

The current implementation will emit a `tensor.reshape` op if any of the dims of the input are not factorable (require more than one dynamic dim in the expansion). However, I could instead only emit reshapes for the dims that need it, and then a `tensor.expand_shape` on the rest of the dims. Whichever is preferable to the reviewer(s).

https://github.com/llvm/llvm-project/pull/76003