Fix UB in modelasm chrinfo handler

Makefile

@@ -461,7 +461,9 @@ else ifeq ($(COMPILER), gcc)
 
     $(C_O_FILES): OPT_LVL := $(GCC_OPT_LVL)
 
-    CFLAGS := $(C_DEFINES) -DAVOID_UB=1 $(INCLUDES) \
+    C_DEFINES += -DAVOID_UB
+
+    CFLAGS := $(C_DEFINES) $(INCLUDES) \
         -EB \
         -march=vr4300 \
         -mabi=32 \

src/lib/modelasm.s

@@ -818,7 +818,11 @@ glabel modelasm00018680
 	beqz   $a1, .L000194a0
 	lw     $t0, 0x4($gp)
 	lhu    $t2, 0x0($a2)
+#ifdef AVOID_UB
+	beqz   $t2, .L0001946c
+#else
 	beqz   $a2, .L0001946c
+#endif
 	lhu    $t1, 0x0($t0)
 	mtc1   $zero, $f29
 	lwc1   $f30, 0x7e0($sp)

src/lib/modelasm_c.c

@@ -453,7 +453,12 @@ bool modelasm00018680(struct modelrenderdata *renderdata, struct model *model)
 			if (model) {
 				t1 = node->rodata->chrinfo.animpart;
 
-				if (anim) {
+#ifdef AVOID_UB
+				if (anim->animnum)
+#else
+				if (anim)
+#endif
+				{
 					if (f30 != 0.0f) {
 						if (anim->flip) {
 							t2ptr8 = skeleton->things[t1];