Codefix: "maybe uninitialized" warnings for linux generic release build (#12838)

src/industry_gui.cpp

@@ -375,7 +375,7 @@ class BuildIndustryWindow : public Window {
 
 		std::string cargostring;
 		size_t numcargo = 0;
-		size_t firstcargo;
+		size_t firstcargo = 0;
 
 		for (size_t j = 0; j < cargolist.size(); j++) {
 			if (!IsValidCargoID(cargolist[j])) continue;

src/newgrf_class.h

@@ -29,7 +29,7 @@ private:
 	static_assert(std::is_base_of_v<NewGRFSpecBase<Tindex>, Tspec>);
 
 	uint ui_count = 0; ///< Number of specs in this class potentially available to the user.
-	Tindex index; ///< Index of class within the list of classes.
+	Tindex index = static_cast<Tindex>(0); ///< Index of class within the list of classes.
 	std::vector<Tspec *> spec; ///< List of specifications.
 
 	/**