[llvm] [BOLT] Avoid large unmapped gaps in compact output files (PR #217873)

[Rafael Auler via llvm-commits]

rafaelauler wrote:

So I guess another question whose answer is still not clear is, how often can we actually reclaim space? Wouldn't linkers most of the time layout all allocatable bytes first, then put non-alloc ones?

https://github.com/llvm/llvm-project/pull/217873