This way downstream tools that read sanitizer output can differentiate between OOM errors reported by sanitizers from other sanitizer errors.
Changes:
- Introduce ErrorIsOOM for checking if a platform-specific error code from an "mmap" is an OOM err.
- Add ReportOOMError which just prepends this error message to the start of a Report call.
- Replace some Reports for OOMs with calls to ReportOOMError.
- Update necessary tests.
The "out of memory" part is redundant now.