fix compiler errors (shadowed vars, comparisons between unsigned + signed, an unused function arg, and a non-static function with no prototype)

src/g_game.c

@@ -3021,7 +3021,6 @@ static void G_DoCompleted(void)
 
 	if ((gottoken = (gametype == GT_COOP && token)))
 	{
-		INT16 i;
 		token--;
 
 		for (i = 0; i < 7; i++)

src/p_enemy.c

@@ -1594,7 +1594,7 @@ void A_CheckBuddy(mobj_t *actor)
 
 // Helper function for the Robo Hood.
 // Don't ask me how it works. Nev3r made it with dark majyks.
-void P_ParabolicMove(mobj_t *actor, fixed_t x, fixed_t y, fixed_t z, fixed_t speed)
+static void P_ParabolicMove(mobj_t *actor, fixed_t x, fixed_t y, fixed_t z, fixed_t speed)
 {
 	fixed_t dh;
 

src/p_inter.c

@@ -2663,6 +2663,8 @@ static inline void P_NiGHTSDamage(mobj_t *target, mobj_t *source)
 	player_t *player = target->player;
 	tic_t oldnightstime = player->nightstime;
 
+	(void)source; // unused
+
 	if (!player->powers[pw_flashing])
 	{
 		angle_t fa;

src/p_user.c

@@ -306,7 +306,6 @@ void P_GiveEmerald(boolean spawnObj)
 	if (spawnObj && playeringame[consoleplayer])
 	{
 		// The Chaos Emerald begins to orbit us!
-		UINT8 em = P_GetNextEmerald();
 		// Only give it to ONE person!
 		mobj_t *emmo = P_SpawnMobjFromMobj(players[consoleplayer].mo, 0, 0, players[consoleplayer].mo->height, MT_GOTEMERALD);
 		P_SetTarget(&emmo->target, players[consoleplayer].mo);

src/st_stuff.c

@@ -1667,7 +1667,7 @@ static void ST_drawNiGHTSHUD(void)
 		else
 			ST_DrawTopLeftOverlayPatch(40, 8 + 5, narrow[(leveltime/2)&7]);
 	}
-	else if (oldspecialstage && total_spherecount < ssspheres)
+	else if (oldspecialstage && total_spherecount < (INT32)ssspheres)
 	{
 		INT32 cfill, amount;
 		const INT32 length = 88;

src/y_inter.c

@@ -329,7 +329,7 @@ void Y_IntermissionDrawer(void)
 		else if (!animatetic && data.spec.bonus.points == 0 && data.spec.passed3[0] != '\0')
 			animatetic = intertic + TICRATE;
 
-		if (animatetic && intertic >= animatetic)
+		if (animatetic && (tic_t)intertic >= animatetic)
 		{
 			const INT32 scradjust = (vid.width/vid.dupx)>>3; // 40 for BASEVIDWIDTH
 			INT32 animatetimer = (intertic - animatetic);