Fix a few cases of UB incl. OoB

Behaviour should be mostly the same but there are some OoB accesses in the menu code where I've had to assume things.

Tests for each OoB case:

- Accessing of layer -1: Select a game file in the "Choose Your Reality" screen.
- Accessing of menu for the 5th player: Die in a mission.

src/game/camera.c

@@ -1,4 +1,5 @@
 #include <ultra64.h>
+#include <string.h>
 #include "constants.h"
 #include "game/atan2f.h"
 #include "game/camera.h"
@@ -600,6 +601,9 @@ bool camIsPosInFovAndVisibleRoom(RoomNum *rooms, struct coord *pos, f32 arg2)
 	RoomNum room;
 	bool hasdata = false;
 	struct drawslot *thisthing;
+#ifdef AVOID_UB
+	static struct drawslot dslot;
+#endif
 	struct screenbox box;
 
 	for (i = 0, room = rooms[i]; room != -1; i++, room = rooms[i]) {
@@ -637,5 +641,10 @@ bool camIsPosInFovAndVisibleRoom(RoomNum *rooms, struct coord *pos, f32 arg2)
 		return false;
 	}
 
+#ifdef AVOID_UB
+	memcpy(&dslot.box, &box, sizeof(box));
+	return camIsPosInScreenBox(pos, arg2, &dslot);
+#else
 	return camIsPosInScreenBox(pos, arg2, (struct drawslot *) &(((u8 *) &box)[-((uintptr_t) &(((struct drawslot *)0)->box))]));
+#endif
 }

src/game/gfxreplace.c

@@ -329,7 +329,11 @@ void gfxReplaceGbiCommands(Gfx *startgdl, Gfx *endgdl, s32 type)
 
 void gfxReplaceGbiCommandsRecursively(struct roomblock *block, s32 type)
 {
+#ifndef AVOID_UB
+	// Sometimes block is NULL when this is called.
+	// If UBSan is being used, this will crash in this instance.
 	if (block->type == ROOMBLOCKTYPE_PARENT);
+#endif
 
 	while (true) {
 		if (!block) {

src/game/menu.c

@@ -3413,8 +3413,14 @@ void menuClose(void)
 
 void func0f0f8120(void)
 {
+#ifdef AVOID_UB
+	u32 mpindex = g_MpPlayerNum % MAX_PLAYERS;
+	struct menudialog *prev = g_Menus[mpindex].curdialog;
+	s32 i;
+#else
 	struct menudialog *prev = g_Menus[g_MpPlayerNum].curdialog;
 	s32 i;
+#endif
 
 	if (g_MenuData.unk66e > 0) {
 		for (i = g_MenuData.unk66e; i >= 0; i--) {
@@ -3422,11 +3428,22 @@ void func0f0f8120(void)
 		}
 	}
 
+#ifdef AVOID_UB
+	mpindex = g_MpPlayerNum;
+	if (mpindex >= MAX_PLAYERS)
+		mpindex -= MAX_PLAYERS;
+	if (g_Menus[mpindex].curdialog == prev) {
+		while (g_Menus[mpindex].depth > 0) {
+			menuPopDialog();
+		}
+	}
+#else
 	if (g_Menus[g_MpPlayerNum].curdialog == prev) {
 		while (g_Menus[g_MpPlayerNum].depth > 0) {
 			menuPopDialog();
 		}
 	}
+#endif
 }
 
 void func0f0f820c(struct menudialogdef *dialogdef, s32 root)
@@ -4340,7 +4357,11 @@ void dialogTick(struct menudialog *dialog, struct menuinputs *inputs, u32 tickfl
 	}
 
 	// Apply default navigational behaviour if requested
+#ifdef AVOID_UB
+	if (usedefaultbehaviour && (tickflags & MENUTICKFLAG_DIALOGISCURRENT) && !dialog->dimmed && g_Menus[g_MpPlayerNum].depth >= 1) {
+#else
 	if (usedefaultbehaviour && (tickflags & MENUTICKFLAG_DIALOGISCURRENT) && !dialog->dimmed) {
+#endif
 		struct menulayer *layer = &g_Menus[g_MpPlayerNum].layers[g_Menus[g_MpPlayerNum].depth - 1];
 
 		if (layer->numsiblings <= 1) {

src/lib/mp3/decoder.c

@@ -2736,8 +2736,8 @@ bool mp3dec000427d8(struct asistream *stream, u32 gr)
 	f32 *sp0c = stream->unk4664[0][0].unk00;
 	s32 i = 0;
 
-	if (stream->window_switching[gr][0] && stream->window_switching[gr][2] == 2) {
-		if (stream->window_switching[gr][4]) {
+	if (stream->window_switching[gr][0] && stream->block_type[gr][0] == 2) {
+		if (stream->mixed_block_flag[gr][0]) {
 			while (i++ < 36) {
 				*(sp10++) = *(sp0c++);
 			}