Fix: don't include xaudio2 if you are not going to compile it

This is more in trend with other files, where if the driver is not
selected, we don't even attempt to compile it.

configure

@@ -123,6 +123,7 @@ AWKCOMMAND='
 		if ($0 == "MSVC"        && "'$os'" != "MSVC")              { next; }
 		if ($0 == "DIRECTMUSIC" && "'$with_direct_music'" == "0")  { next; }
 		if ($0 == "FLUIDSYNTH"  && "'$fluidsynth'" == "" )         { next; }
+		if ($0 == "USE_XAUDIO2" && "'$with_xaudio2'" == "0")       { next; }
 		if ($0 == "USE_THREADS" && "'$with_threads'" == "0")       { next; }
 		if ($0 == "USE_SSE"     && "'$with_sse'" != "1")           { next; }
 

projects/generate

@@ -138,6 +138,7 @@ load_main_data() {
 			if ($0 == "MSVC"        && "'$os'" != "MSVC")              { next; }
 			if ($0 == "DIRECTMUSIC" && "'$enable_directmusic'" != "1") { next; }
 			if ($0 == "FLUIDSYNTH"  && "'$enable_fluidsynth'" != "1")  { next; }
+			if ($0 == "USE_XAUDIO2" && "'$with_xaudio2'" == "0")       { next; }
 			if ($0 == "USE_THREADS" && "'$with_threads'" == "0")       { next; }
 
 			skip += 1;

projects/generate.vbs

@@ -180,6 +180,7 @@ Sub load_main_data(filename, ByRef vcxproj, ByRef filters, ByRef files)
 						line = "DIRECTMUSIC" Or _
 						line = "AI" Or _
 						line = "USE_SSE" Or _
+						line = "USE_XAUDIO2" Or _
 						line = "USE_THREADS" _
 					) Then skip = skip + 1
 					deep = deep + 1

source.list

@@ -1141,7 +1141,9 @@ sound/null_s.cpp
 	#end
 	#if WIN32
 		sound/win32_s.cpp
-		sound/xaudio2_s.cpp
+		#if USE_XAUDIO2
+			sound/xaudio2_s.cpp
+		#end
 	#end
 #end