Update audio_stream_effects.c (raysan5#3618)

* Update audio_stream_effects.c

This may slightly improve performance and be more welcoming for new users despite being an more advanced feature. 
void * usually throws an error in most compilers and it would be better to just avoid it.

Also added <stdbool.h> because booleans are, sometimes, not defined by <stddef.h>.

* Update audio_stream_effects.c

examples/audio/audio_stream_effects.c

@@ -2,7 +2,7 @@
 *
 *   raylib [audio] example - Music stream processing effects
 *
-*   Example originally created with raylib 4.2, last time updated with raylib 4.2
+*   Example originally created with raylib 4.2, last time updated with raylib 5.0
 *
 *   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
 *   BSD-like license that allows static linking with closed source software
@@ -13,7 +13,7 @@
 
 #include "raylib.h"
 
-#include <stdlib.h>         // Required for: NULL
+#include <stdlib.h> // Required for: NULL
 
 // Required delay effect variables
 static float *delayBuffer = NULL;
@@ -149,13 +149,17 @@ static void AudioProcessEffectLPF(void *buffer, unsigned int frames)
     static const float cutoff = 70.0f / 44100.0f; // 70 Hz lowpass filter
     const float k = cutoff / (cutoff + 0.1591549431f); // RC filter formula
 
+    // Converts the buffer data before using it
+    float *bufferData = (float *)buffer;
     for (unsigned int i = 0; i < frames*2; i += 2)
     {
-        float l = ((float *)buffer)[i], r = ((float *)buffer)[i + 1];
+        const float l = bufferData[i];
+        const float r = bufferData[i + 1];
+
         low[0] += k * (l - low[0]);
         low[1] += k * (r - low[1]);
-        ((float *)buffer)[i] = low[0];
-        ((float *)buffer)[i + 1] = low[1];
+        bufferData[i] = low[0];
+        bufferData[i + 1] = low[1];
     }
 }
 
@@ -176,4 +180,4 @@ static void AudioProcessEffectDelay(void *buffer, unsigned int frames)
         delayBuffer[delayWriteIndex++] = ((float *)buffer)[i + 1];
         if (delayWriteIndex == delayBufferSize) delayWriteIndex = 0;
     }
-}
+}