- don't let CHANF_AUTO hijack other channels.

With CHANF_OVERLAP this isn't needed anymore - any sound started on CHAN_AUTO can actually play on this channel with overlap implicitly allowed.
This has the added advantage that these sounds can be reliably accessed with other function by using CHAN_AUTO.

src/common/2d/v_2ddrawer.cpp

@@ -397,6 +397,7 @@ void F2DDrawer::SetColorOverlay(PalEntry color, float alpha, PalEntry &vertexcol
 void F2DDrawer::AddTexture(FGameTexture* img, DrawParms& parms)
 {
 	if (parms.style.BlendOp == STYLEOP_None) return;	// not supposed to be drawn.
+	assert(img && img->isValid());
 
 	double xscale = parms.destwidth / parms.texwidth;
 	double yscale = parms.destheight / parms.texheight;

src/common/audio/sound/s_sound.cpp

@@ -494,26 +494,9 @@ FSoundChan *SoundEngine::StartSound(int type, const void *source,
 	int seen = 0;
 	if (source != NULL && channel == CHAN_AUTO)
 	{
-		// Select a channel that isn't already playing something.
-		// Try channel 0 first, then travel from channel 7 down.
-		if (!IsChannelUsed(type, source, 0, &seen))
-		{
-			channel = 0;
-		}
-		else
-		{
-			for (channel = 7; channel > 0; --channel)
-			{
-				if (!IsChannelUsed(type, source, channel, &seen))
-				{
-					break;
-				}
-			}
-			if (channel == 0)
-			{ // Crap. No free channels.
-				return NULL;
-			}
-		}
+		// In the old sound system, 'AUTO' hijacked one of the other channels.
+		// Now, with CHANF_OVERLAP at our disposal that isn't needed anymore. Just set the flag and let all sounds play on channel 0.
+		chanflags |= CHANF_OVERLAP;
 	}
 
 	// If this actor is already playing something on the selected channel, stop it.

src/common/thirdparty/sfmt/SFMT.h

@@ -28,6 +28,8 @@
  * unsigned int and 64-bit unsigned int in hexadecimal format.
  */
 
+#include <inttypes.h>
+
 #ifndef SFMT_H
 #define SFMT_H