[clang] [llvm] [Support] Make format_object non-virtual (PR #206319)

[Alexis Engelke via cfe-commits]

aengelke wrote:

[c-t-t stage2-clang -0.10%](https://llvm-compile-time-tracker.com/compare.php?from=92f01b267efe262a096baa433665c169cd53ff2c&to=0c948eb5d54a86be960cceb83538132556c40b32&stat=size-data)

As a general note, size-data serves as a reasonably good proxy for the number or relocations (it includes .data, .tdata, .data.rel.ro, .{init,fini}_array, and .got*). E.g. in my local build, size-data is 1886k (~471 4k pages) and there are 154395 dynamic relocations (=12.5 bytes per 8 byte reloc => we can assume that all data pages will be faulted on startup -- perf reports that _dl_relocate_object causes 521 page faults.)

https://github.com/llvm/llvm-project/pull/206319