[compiler-rt] [tsan] Fix ASLR edge case, and improve diagnostics (PR #97125)

[Thurston Dang via llvm-commits]

thurstond wrote:

Reproducer for the edge case:

empty.c:
```
#include <stdio.h>

int main (int argc, char* argv[]) {
    return 0;
}
```
```
$ clang -fsanitize=thread empty.c -o empty
# Adjust -P 200 (max parallelism) to taste
$ seq 1 50000000 | xargs -i -P 200 ./empty
# Now wait. The chance of the edge case is roughly one in 3 million.
```


https://github.com/llvm/llvm-project/pull/97125