[llvm] [MC,COFF] .safeseh: avoid changeSection (PR #132624)

[Fangrui Song via llvm-commits]

MaskRay wrote:

(While I believe this is improvement, I don't really know `.safeseh` (invented by LLVM, not in binutils). I think we lack `-filetype=obj -mtriple=i686-windows-msvc` tests to actually exercise the MCWinCOFFStreamer code path (object file emission), but I don't know how to properly test it. )

https://github.com/llvm/llvm-project/pull/132624