Initialize class/struct variables with default values in core/ and drivers/

core/core_constants.cpp

@@ -38,10 +38,10 @@
 struct _CoreConstant {
 #ifdef DEBUG_METHODS_ENABLED
 	StringName enum_name;
-	bool ignore_value_in_docs;
+	bool ignore_value_in_docs = false;
 #endif
 	const char *name;
-	int value;
+	int value = 0;
 
 	_CoreConstant() {}