AK: Call fmod() only when necessary in sin(), cos()

Running benchmark 'bench_trig_cos'.
Completed benchmark 'bench_trig_cos' in 132ms
Running benchmark 'bench_trig_cosf'.
Completed benchmark 'bench_trig_cosf' in 92ms
Running benchmark 'bench_trig_sin'.
Completed benchmark 'bench_trig_sin' in 112ms
Running benchmark 'bench_trig_sinf'.
Completed benchmark 'bench_trig_sinf' in 107ms

Author: nico

AK/Math.h

@@ -688,7 +688,8 @@ constexpr T sin(T angle)
     if (angle < 0)
         return -sin(-angle);
 
-    angle = fmod(angle, 2 * Pi<T>);
+    if (angle >= 2 * Pi<T>)
+        angle = fmod(angle, 2 * Pi<T>);
 
     if (angle >= Pi<T>)
         return -sin(angle - Pi<T>);
@@ -743,7 +744,8 @@ constexpr T cos(T angle)
     if (angle < 0)
         return cos(-angle);
 
-    angle = fmod(angle, 2 * Pi<T>);
+    if (angle >= 2 * Pi<T>)
+        angle = fmod(angle, 2 * Pi<T>);
 
     if (angle >= Pi<T>)
         return -cos(angle - Pi<T>);