Better error message when receiving SIGBUS

[Forestryks]

While we have a disk space check to avoid getting SIGBUS when writing to mmaped output file, this check is a bit racy as available disk space can go down between this check and actual write. In this feature we add a special handling for SIGBUS, that will change error message from

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.

to

Linker received SIGBUG which most likely means that there is insufficient disk space available. If you think this is not the case, please reach out internally for assistance.