libcamera: log: Add a LogFatal log level

The LogFatal log level is similar to the LogError level, but
additionally abort program execution. This is useful to implement
assertion handlers.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/include/log.h

@@ -16,6 +16,7 @@ enum LogSeverity {
 	LogInfo,
 	LogWarning,
 	LogError,
+	LogFatal,
 };
 
 class LogMessage
@@ -30,6 +31,7 @@ public:
 
 private:
 	std::ostringstream msgStream;
+	LogSeverity severity_;
 };
 
 #define LOG(severity) LogMessage(__FILE__, __LINE__, Log##severity).stream()