Add rand.h for non-qrand.c rand functions (#1684)

* sync rand.h with related oot PR

* fix

* yeet comment

include/rand.h

@@ -0,0 +1,9 @@
+#ifndef RAND_H
+#define RAND_H
+
+#include "libc64/qrand.h"
+
+f32 Rand_ZeroFloat(f32 scale);
+f32 Rand_CenteredFloat(f32 scale);
+
+#endif

include/z64.h

@@ -22,6 +22,7 @@
 #include "message_data_static.h"
 #include "padmgr.h"
 #include "padutils.h"
+#include "rand.h"
 #include "regs.h"
 #include "scheduler.h"
 #include "segmented_address.h"

include/z64math.h

@@ -244,8 +244,6 @@ f32 Math_Factorial(s32 n);
 f32 Math_PowF(f32 base, s32 exp);
 f32 Math_SinF(f32 rad);
 f32 Math_CosF(f32 rad);
-f32 Rand_ZeroFloat(f32 scale);
-f32 Rand_CenteredFloat(f32 scale);
 
 s16 Math_Atan2S(f32 y, f32 x);
 f32 Math_Atan2F(f32 y, f32 x);