Fix activeTextureId to have MAX_BATCH_ACTIVE_TEXTURES elements instead of the hardcoded 4 (#1674)

src/rlgl.h

@@ -825,7 +825,7 @@ typedef struct rlglData {
         Texture2D shapesTexture;            // Texture used on shapes drawing (usually a white pixel)
         Rectangle shapesTextureRec;         // Texture source rectangle used on shapes drawing
         unsigned int defaultTextureId;      // Default texture used on shapes/poly drawing (required by shader)
-        unsigned int activeTextureId[mi">4];    // Active texture ids to be enabled on batch drawing (0 active by default)
+        unsigned int activeTextureId[n">MAX_BATCH_ACTIVE_TEXTURES];    // Active texture ids to be enabled on batch drawing (0 active by default)
         unsigned int defaultVShaderId;      // Default vertex shader id (used by default shader program)
         unsigned int defaultFShaderId;      // Default fragment shader Id (used by default shader program)
         Shader defaultShader;               // Basic shader, support vertex color and diffuse texture