[llvm] [MC] Reduce size of MCDataFragment by 8 bytes (PR #95293)

[Fangrui Song via llvm-commits]

MaskRay wrote:

Before the removal of `SubsectionNumber` (#95077) and `IsBeingLaidOut` (9d0754ada5dbbc0c009bcc2f7824488419cc5530), `sizeof(MCDataFragment)` was 232  It's now 224. Yes! With some bit fields we can decrease it to 216.

https://github.com/llvm/llvm-project/pull/95293