add multi channel audio to raudio (#895)

* added multi channel sound replay to raudio
added -fPIC to Makefile for Linux
added simple lighting and audio multi channel to examples Makefile

* not properly reporting audio buffer pool size...

examples/audio/audio_multichannel_sound.c

@@ -0,0 +1,116 @@
+
+/*
+* This example was coded to demonstrate multi channel audio changes added to raylib
+*
+*   This example has been created using raylib (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   This example Copyright (c) 2018 Chris Camacho (codifies) http://bedroomcoders.co.uk/captcha/
+*
+* THIS EXAMPLE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+* OTHER DEALINGS IN THE SOFTWARE.
+*
+* This example may be freely redistributed.
+*/
+
+#include "raylib.h"
+#include <stdio.h> // sprintf
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [audio] abuse!");
+
+    InitAudioDevice();      // Initialize audio device
+
+    Sound fxWav = LoadSound("resources/sound.wav");         // Load WAV audio file
+    Sound fxOgg = LoadSound("resources/tanatana.ogg");      // Load OGG audio file
+
+
+    //InitPlayBufferPool();
+
+
+
+    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+    int frame = 0;
+    // Main game loop
+
+    // old system still works alongside
+    SetSoundVolume(fxWav, 0.2); // effects all mutltiplay replay (really annoying sound!!!)
+    PlaySound(fxOgg);
+
+    bool inhibitWav = false;
+    bool inhibitOgg = false;
+    int maxFrame = 60;
+    int numberPlaying = 0;
+
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        frame++;
+
+        if (IsKeyDown(KEY_ENTER)) { inhibitWav=true; } else { inhibitWav=false; }
+        if (IsKeyDown(KEY_SPACE)) { inhibitOgg=true; } else { inhibitOgg=false; }
+
+        // deliberatly hammer the play pool to see what dropping old
+        // pool entries sounds like....
+        if (frame % 5==0) {
+           if (!inhibitWav) PlaySoundEx(fxWav);
+        }
+        if (frame==maxFrame) {
+            if (!inhibitOgg) PlaySoundEx(fxOgg);
+            frame=0;
+            maxFrame = GetRandomValue(6,12);
+        }
+
+        numberPlaying = ConcurrentPlayChannels();
+
+        //----------------------------------------------------------------------------------
+
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+            char msg[1024];
+            DrawText("multichannel sound abuse!", 200, 180, 20, LIGHTGRAY);
+            DrawText("Space to inhibit new ogg triggering", 200, 200, 20, LIGHTGRAY);
+            DrawText("Enter to inhibit new wav triggering", 200, 220, 20, LIGHTGRAY);
+
+            sprintf(msg,"concurrently playing %i", numberPlaying);
+            DrawText(msg, 200, 280, 20, LIGHTGRAY);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+
+
+    // you MUST stop the buffer pool before unloading
+    // any Sounds it might have used...
+    StopPlayBufferPool();
+
+    UnloadSound(fxWav);     // Unload sound data
+    UnloadSound(fxOgg);     // Unload sound data
+
+    CloseAudioDevice();     // Close audio device
+
+    CloseWindow();          // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}