S_StopMusicCredit: Make killing a music credit a request, not a guarantee

Fixes some menu events causing Stereo-caused music credits to disappear

src/d_main.c

@@ -1047,7 +1047,7 @@ void D_ClearState(void)
 	if (rendermode != render_none)
 		V_SetPaletteLump("PLAYPAL");
 
-	cursongcredit.def = NULL;
+	S_StopMusicCredit();
 	S_StopSounds();
 
 	if (gamedata && gamedata->deferredsave)

src/f_finale.c

@@ -310,7 +310,7 @@ void F_StartCustomCutscene(INT32 cutscenenum, boolean precutscene, boolean reset
 
 void F_StartIntro(void)
 {
-	cursongcredit.def = NULL;
+	S_StopMusicCredit();
 
 	if (gamestate)
 	{

src/k_menufunc.c

@@ -376,7 +376,7 @@ void M_PlayMenuJam(void)
 	if (challengesmenu.pending)
 	{
 		S_StopMusic();
-		cursongcredit.def = NULL;
+		S_StopMusicCredit();
 
 		loserclubpermitted = true;
 		return;
@@ -390,7 +390,7 @@ void M_PlayMenuJam(void)
 		if (refMenu->music[0] == '.' && refMenu->music[1] == '\0')
 		{
 			S_StopMusic();
-			cursongcredit.def = NULL;
+			S_StopMusicCredit();
 			return;
 		}
 		else if (!loserclub)

src/s_sound.c

@@ -1665,7 +1665,7 @@ void S_SoundTestStop(void)
 	soundtest.autosequence = false;
 
 	S_StopMusic();
-	cursongcredit.def = NULL;
+	S_StopMusicCredit();
 
 	soundtest.currenttime = 0;
 	soundtest.sequencemaxtime = 0;
@@ -2147,6 +2147,14 @@ void S_ShowMusicCredit(void)
 	cursongcredit.trans = NUMTRANSMAPS;
 }
 
+void S_StopMusicCredit(void)
+{
+	if (S_PlaysimMusicDisabled())
+		return;
+
+	cursongcredit.def = NULL;
+}
+
 /// ------------------------
 /// Music Status
 /// ------------------------

src/s_sound.h

@@ -247,6 +247,7 @@ void S_LoadMusicDefs(UINT16 wadnum);
 void S_InitMusicDefs(void);
 musicdef_t *S_FindMusicDef(const char *name, UINT8 *i);
 void S_ShowMusicCredit(void);
+void S_StopMusicCredit(void);
 
 //
 // Music Seeking