ipa: raspberrypi: Return an error code from Algorithm::read()

When encountering errors, the Algorithm::read() function either uses
LOG(Fatal) or throws exceptions from the boost property_tree functions.
To prepare for replacing boost JSON parse with the YamlParser class,
give the Algorithm::read() function the ability to return an error code,
and propagate it all the way to the IPA module init() function.

All algorithm classes return a hardcoded 0 value for now, subsequent
commits will change that.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Tested-by: Naushir Patuck <naush@raspberrypi.com>

src/ipa/raspberrypi/controller/controller.h

@@ -41,7 +41,7 @@ public:
 	Controller(char const *jsonFilename);
 	~Controller();
 	Algorithm *createAlgorithm(char const *name);
-	void read(char const *filename);
+	int read(char const *filename);
 	void initialise();
 	void switchMode(CameraMode const &cameraMode, Metadata *metadata);
 	void prepare(Metadata *imageMetadata);