audio: Removed internal SDL_audiomem.h and macros.

I think this was important for SDL 1.2 because some targets needed
special device memory for DMA buffers or locked memory buffers for use in
hardware interrupts or something, but since it just defines to SDL_malloc
and SDL_free now, I took it out for clarity's sake.

VisualC/SDL/SDL.vcxproj

@@ -294,7 +294,6 @@
     <ClInclude Include="resource.h" />
     <ClInclude Include="..\..\src\audio\SDL_audio_c.h" />
     <ClInclude Include="..\..\src\audio\SDL_audiodev_c.h" />
-    <ClInclude Include="..\..\src\audio\SDL_audiomem.h" />
     <ClInclude Include="..\..\src\render\software\SDL_blendfillrect.h" />
     <ClInclude Include="..\..\src\render\software\SDL_blendline.h" />
     <ClInclude Include="..\..\src\render\software\SDL_blendpoint.h" />

VisualC/SDL/SDL.vcxproj.filters

@@ -230,7 +230,6 @@
     <ClInclude Include="resource.h" />
     <ClInclude Include="..\..\src\audio\SDL_audio_c.h" />
     <ClInclude Include="..\..\src\audio\SDL_audiodev_c.h" />
-    <ClInclude Include="..\..\src\audio\SDL_audiomem.h" />
     <ClInclude Include="..\..\src\render\software\SDL_blendfillrect.h" />
     <ClInclude Include="..\..\src\render\software\SDL_blendline.h" />
     <ClInclude Include="..\..\src\render\software\SDL_blendpoint.h" />

VisualC/SDL/SDL_VS2008.vcproj

@@ -771,10 +771,6 @@
 			RelativePath="..\..\src\audio\SDL_audiodev_c.h"
 			>
 		</File>
-		<File
-			RelativePath="..\..\src\audio\SDL_audiomem.h"
-			>
-		</File>
 		<File
 			RelativePath="..\..\src\audio\SDL_audiotypecvt.c"
 			>