C++: Revert benign change of return type from 'unsigned int' to 'int' in testcase, and add 'GOOD' annotation to the testcase

Author: andersfugmann

cpp/ql/test/query-tests/Likely Bugs/Conversion/ImplicitDowncastFromBitfield/test.cpp

@@ -2,8 +2,8 @@ typedef struct {
 	int x : 24;
 } my_struct;
 
-unsigned int getX1(my_struct m) {
-	return m.x;
+int getX1(my_struct m) {
+	return m.x; // GOOD
 }
 
 short getX2(my_struct m) {