[llvm] [SLP]Initial support for copyable elements (non-schedulable only) (PR #140279)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> FYI this has some compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=36089e5d983fe9ae00f497c2d500f37227f82db1&to=e202dba288edd47f1b370cc43aa8cd36a924e7c1&stat=instructions:u Some files with large impact are libclamav_nsis_LZMADecode.c (+8%) and zlib_inflate.c (+4%).

Reverted for now in a415d68e48c4672c63082192626fec9bf9ae9c2c, will try to fix 

https://github.com/llvm/llvm-project/pull/140279