[compiler-rt] [Profile] Disable continuous mode when reset to default.profraw due to malformed LLVM_PROFILE_FILE. (PR #74879)

[David Li via llvm-commits]

david-xl wrote:

> > what about printing an error and immediately aborting when LLVM_PROFILE_FILE is invalid?
> 
> I think this is better than falls back to default.profraw with a warning, which is hard to notice. Or we can simply allow multiple `%c` and enable continuous mode as this shouldn't cause any ambiguity. But multiple `%m` might cause ambiguity because it can have `%1m` and `%2m` at the same time and cause ambiguity.

Currently all parsing errors are treated as warnings. Perhaps a runtime option can be added in the future to turn them into hard errors. 

https://github.com/llvm/llvm-project/pull/74879