Fix #12818: during Hostile Takeover, profit was calculated wrongly (#12819)

(cherry picked from commit 21813fbe8b)

src/economy.cpp

@@ -209,7 +209,7 @@ Money CalculateHostileTakeoverValue(const Company *c)
 	}
 
 	for (int quarter = 0; quarter < 4; quarter++) {
-		value += std::max<Money>(c->old_economy[quarter].income - c->old_economy[quarter].expenses, 0) * 2;
+		value += std::max<Money>(c->old_economy[quarter].income + c->old_economy[quarter].expenses, 0) * 2;
 	}
 
 	return std::max<Money>(value, 1);