[TSan][compiler-rt] Defer symbolization of Reports to as late as possible (#151120)
This is the refactoring portion of:
https://github.com/llvm/llvm-project/pull/149516. My aim is for this
change to replicate current behaviour - just with Symbolization done
explicitly (and later than previously).
This change will enable us to perform symboliaztion after releasing the
locks in `OutputReport`; this is necessary on Apple platforms in order
to avoid a deadlock.