[llvm] [DebugInfo][DWARF] Set is_stmt on first non-line-0 instruction in BB (PR #105524)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

> Could you put this behind a flag or revert this for now

I can revert it, at least until the next patch is ready to land. I've tried to investigate this locally to see if the situation is improved by the next patch along, but my local build isn't showing anywhere close to the same increase - I've got .debug_line size increasing by 1.3% as a result of this commit. When you say "Debug", does that mean the CMake "Debug" option, or a release build with debug info enabled?

https://github.com/llvm/llvm-project/pull/105524