port: set g_MaxExplosions to 6 by default

src/game/explosions.c

@@ -35,7 +35,7 @@
 #endif
 
 struct explosion *g_Explosions;
-s32 g_MaxExplosions;
+s32 g_MaxExplosions = MAX_EXPLOSIONS_DEFAULT;
 
 s32 g_ExplosionShakeTotalTimer = 0;
 s32 g_ExplosionShakeIntensityTimer = 0;

src/include/constants.h

@@ -27,6 +27,7 @@
 #define MAX_ROOMPROPLISTCHUNKS 256
 #define MAX_SQUADRONS          16
 #define MAX_TEAMS              8
+#define MAX_EXPLOSIONS_DEFAULT 6
 
 #define NUM_BOTDIFFS          6
 #define NUM_CYCLEABLE_WEAPONS 45