slightly optimize Vector3Normalize (#2982)

src/raymath.h

@@ -703,12 +703,14 @@ RMAPI Vector3 Vector3Normalize(Vector3 v)
     Vector3 result = v;
 
     float length = sqrtf(v.x*v.x + v.y*v.y + v.z*v.z);
-    if (length == 0.0f) length = 1.0f;
-    float ilength = 1.0f/length;
+    if (length != 0.0f) 
+    {
+        float ilength = 1.0f/length;
 
-    result.x *= ilength;
-    result.y *= ilength;
-    result.z *= ilength;
+        result.x *= ilength;
+        result.y *= ilength;
+        result.z *= ilength;
+    }
 
     return result;
 }