Include the OpenAL headers using the "al.h" form, as recommended by its CMake finder script

CMakeLists.txt

@@ -175,6 +175,7 @@ find_package(GLEW REQUIRED)
 
 if (OPENAL_SOUND)
     find_package(OpenAL REQUIRED)
+    include_directories(${OPENAL_INCLUDE_DIR})
     find_package(LibSndFile REQUIRED)
 endif()
 

src/sound/oalsound/alsound.h

@@ -32,7 +32,7 @@
 #include <map>
 #include <string>
 
-#include <AL/al.h>
+#include <al.h>
 
 
 class ALSound : public CSoundInterface

src/sound/oalsound/buffer.h

@@ -30,7 +30,7 @@
 #include <vector>
 #include <array>
 
-#include <AL/al.h>
+#include <al.h>
 #include <sndfile.h>
 
 class Buffer

src/sound/oalsound/channel.h

@@ -30,8 +30,8 @@
 #include <deque>
 #include <cassert>
 
-#include <AL/al.h>
-#include <AL/alc.h>
+#include <al.h>
+#include <alc.h>
 
 struct SoundOper
 {

src/sound/oalsound/check.h

@@ -18,11 +18,11 @@
 
 #pragma once
 
-#include <AL/al.h>
-#include <AL/alc.h>
-
 #include "common/logger.h"
 
+#include <al.h>
+#include <alc.h>
+
 static ALenum CODE = AL_NO_ERROR;
 
 inline bool alCheck()