Fixed a crash when the attacker dies while performing a desparate attack.

The crash seemed only to happen under Windows but valgrind also
complained (bug #10496)

changelog

@@ -44,6 +44,9 @@ Version 1.3.12+svn:
      * The MP server can send gzipped data depending on a hidden parameter 
        which is off by default.
      * The campaign server sends and receives binary_wml.
+   * fixed a crash when the attacker dies while performing a desparate attack.
+     The crash seemed only to happen under Windows but valgrind also
+     complained (bug #10496)
 
 Version 1.3.12:
  * campaigns:

src/ai.cpp

@@ -1071,7 +1071,19 @@ bool ai::do_combat(std::map<gamemap::location,paths>& possible_moves, const move
 	}
 }
 
-void ai_interface::attack_enemy(const location& u, const location& target, int weapon, int def_weapon)
+//! This function should be called to attack an enemy.
+//!
+//! @param u            The location of the attacking unit. (Note this shouldn't
+//!                     be a reference since attack::attack() can invalidate the
+//!                     unit_map and references to the map are also invalid then.)
+//! @param target       The location of the target unit. This unit must be in 
+//!                     range of the attacking unit's weapon. (See note at param u.)
+//! @param weapon       The number of the weapon (0-based) which should be used 
+//!                     by the attacker. (It must be a valid weapon of the attacker.)
+//! @param def_weapon   The number of the weapon (0-based) which should be used 
+//!                     by the defender. (It must be a valid weapon of the defender.)
+void ai_interface::attack_enemy(const location u, 
+		const location target, int weapon, int def_weapon)
 {
 	// Stop the user from issuing any commands while the unit is attacking
 	const events::command_disabler disable_commands;

src/ai_interface.hpp

@@ -103,12 +103,7 @@ public:
 
 protected:
 	//! This function should be called to attack an enemy.
-	//! 'attacking_unit':	the location of the attacking unit
-	//! 'target':			the location of the target unit.
-	//						This unit must be in range of the attacking unit's weapon
-	//! 'att_weapon':		the number of the weapon (0-based) which should be used in the attack.
-	//!					This must be a valid weapon of the attacking unit.
-	void attack_enemy(const location& attacking_unit, const location& target, int att_weapon, int def_weapon);
+	void attack_enemy(const location u, const location target, int att_weapon, int def_weapon);
 
 	//! This function should be called to move a unit.
 	//! Once the unit has been moved, its movement allowance is set to 0.

src/replay.cpp

@@ -1026,6 +1026,8 @@ bool do_replay(game_display& disp, const gamemap& map, const game_data& gameinfo
 				replay::throw_error("no destination/source found in attack\n");
 			}
 
+			//we must get locations by value instead of by references, because the iterators
+			//may become invalidated later
 			const gamemap::location src(*source, game_events::get_state_of_game());
 			const gamemap::location dst(*destination, game_events::get_state_of_game());