Remove obsolete SDL2_mixer macros

SDL2_Mixer v2.6.0 promoted some identifiers from C preprocessor macros
to proper functions. This commit removes Pascal functions that imitated
said macros and replaces them with external function declarations.

Author: suve

units/sdl2_mixer.pas

@@ -196,7 +196,7 @@ function Mix_QuerySpec(frequency: pcint; format: pcuint16; channels: pcint): cin
 
   {* Load a wave file or a music (.mod .s3m .it .xm) file *}
 function Mix_LoadWAV_RW(src: PSDL_RWops; freesrc: cint): PMix_Chunk cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_LoadWAV_RW' {$ENDIF} {$ENDIF};
-function Mix_LoadWAV(_file: PAnsiChar): PMix_Chunk;
+function Mix_LoadWAV(_file: PAnsiChar): PMix_Chunk cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_LoadWAV' {$ENDIF} {$ENDIF};
 function Mix_LoadMUS(_file: PAnsiChar): PMix_Music cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_LoadMUS' {$ENDIF} {$ENDIF};
 
   {* Load a music file from an SDL_RWop object (Ogg and MikMod specific currently)
@@ -651,15 +651,17 @@ function Mix_GroupNewer(tag: cint): cint cdecl; external MIX_LibName {$IFDEF DEL
      If 'loops' is -1, loop inifinitely (~65000 times).
      Returns which channel was used to play the sound.
   *}
-function Mix_PlayChannel(channel: cint; chunk: PMix_Chunk; loops: cint): cint;
+function Mix_PlayChannel(channel: cint; chunk: PMix_Chunk; loops: cint): cint; cdecl;
+  external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_PlayChannel' {$ENDIF} {$ENDIF};
   {* The same as above, but the sound is played at most 'ticks' milliseconds *}
 function Mix_PlayChannelTimed(channel: cint; chunk: PMix_Chunk; loops: cint; ticks: cint): cint cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_PlayChannelTimed' {$ENDIF} {$ENDIF};
 function Mix_PlayMusic(music: PMix_Music; loops: cint): cint cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_PlayMusic' {$ENDIF} {$ENDIF};
 
   {* Fade in music or a channel over "ms" milliseconds, same semantics as the "Play" functions *}
 function Mix_FadeInMusic(music: PMix_Music; loops: cint; ms: cint): cint cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_FadeInMusic' {$ENDIF} {$ENDIF};
 function Mix_FadeInMusicPos(music: PMix_Music; loops: cint; ms: cint; position: Double): cint cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_FadeInMusicPos' {$ENDIF} {$ENDIF};
-function Mix_FadeInChannel(channel: cint; chunk: PMix_Chunk; loops: cint; ms: cint): cint;
+function Mix_FadeInChannel(channel: cint; chunk: PMix_Chunk; loops: cint; ms: cint): cint; cdecl;
+  external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_FadeInChannel' {$ENDIF} {$ENDIF};
 function Mix_FadeInChannelTimed(channel: cint; chunk: PMix_Chunk; loops: cint; ms: cint; ticks: cint): cint cdecl; external MIX_LibName {$IFDEF DELPHI} {$IFDEF MACOS} name '_MIX_FadeInChannelTimed' {$ENDIF} {$ENDIF};
 
   {* Set the volume in the range of 0-128 of a specific channel or chunk.
@@ -848,19 +850,4 @@ procedure MIX_VERSION(Out X: TSDL_Version);
   SDL_MIXER_VERSION(X);
 end;
 
-function Mix_FadeInChannel(channel: cint; chunk: PMix_Chunk; loops: cint; ms: cint): cint;
-begin
-  Result := Mix_FadeInChannelTimed(channel, chunk, loops, ms, -1);
-end;
-
-function Mix_PlayChannel(channel: cint; chunk: PMix_Chunk; loops: cint): cint;
-begin
-  Result := Mix_PlayChannelTimed(channel, chunk, loops, -1);
-end;
-
-function Mix_LoadWAV(_file: PAnsiChar): PMix_Chunk;
-begin
-  Result := Mix_LoadWAV_RW(SDL_RWFromFile(_file, 'rb'), 1);
-end;
-
 end.