moved GAIN_UP for vampire to global scope (avoid memory dups)

src/vampire.h

@@ -2,6 +2,7 @@
 #define __VAMPIRE_H__
 #include "characters.h"
 
+const int GAIN_HP = 5;
 
 class vampire final: public character {
 public:
@@ -9,9 +10,7 @@ public:
         virtual result attack(const direction dir,
                               const character_list &chlist) override;
         virtual result get_hit(const enum race &race, const int atk,
-                               const float hit_rate) override;
-private:
-        const int GAIN_HP = 5;
+                               const float hit_rate) override;        
 };
 
 #endif