pulseaudio: Revert "pulseaudio: Require PulseAudio 5.0 or later for SDL3."

This reverts commit 6fd0613ac841b2e4384ded3097a6453b7b7b5e53.

Turns out that the Steam Runtime is still on PulseAudio 1.1, and the only
thing we (currently) need a newer Pulse for is pa_threaded_mainloop_set_name,
so let's just go back to treating that symbol as optional.

We might need to force a higher version at some point, but it's not worth it
over this.

cmake/sdlchecks.cmake

@@ -162,7 +162,7 @@ endmacro()
 # - HAVE_SDL_LOADSO opt
 macro(CheckPulseAudio)
   if(SDL_PULSEAUDIO)
-    set(PulseAudio_PKG_CONFIG_SPEC "libpulse>=5.0")
+    set(PulseAudio_PKG_CONFIG_SPEC "libpulse>=0.9.15")
     pkg_check_modules(PC_PULSEAUDIO IMPORTED_TARGET ${PulseAudio_PKG_CONFIG_SPEC})
     if(PC_PULSEAUDIO_FOUND)
       set(HAVE_PULSEAUDIO TRUE)

src/audio/pulseaudio/SDL_pulseaudio.c

@@ -188,7 +188,6 @@ static int load_pulseaudio_syms(void)
     SDL_PULSEAUDIO_SYM(pa_threaded_mainloop_wait);
     SDL_PULSEAUDIO_SYM(pa_threaded_mainloop_signal);
     SDL_PULSEAUDIO_SYM(pa_threaded_mainloop_free);
-    SDL_PULSEAUDIO_SYM(pa_threaded_mainloop_set_name);
     SDL_PULSEAUDIO_SYM(pa_operation_get_state);
     SDL_PULSEAUDIO_SYM(pa_operation_cancel);
     SDL_PULSEAUDIO_SYM(pa_operation_set_state_callback);
@@ -225,6 +224,15 @@ static int load_pulseaudio_syms(void)
     SDL_PULSEAUDIO_SYM(pa_stream_set_read_callback);
     SDL_PULSEAUDIO_SYM(pa_context_get_server_info);
 
+    /* optional */
+#ifdef SDL_AUDIO_DRIVER_PULSEAUDIO_DYNAMIC
+    load_pulseaudio_sym("pa_threaded_mainloop_set_name", (void **)(char *)&PULSEAUDIO_pa_threaded_mainloop_set_name);
+#elif (PA_PROTOCOL_VERSION >= 29)
+    PULSEAUDIO_pa_threaded_mainloop_set_name = pa_threaded_mainloop_set_name;
+#else
+    PULSEAUDIO_pa_threaded_mainloop_set_name = NULL;
+#endif
+
     return 0;
 }
 
@@ -310,7 +318,9 @@ static int ConnectToPulseServer(void)
         return SDL_SetError("pa_threaded_mainloop_new() failed");
     }
 
-    PULSEAUDIO_pa_threaded_mainloop_set_name(pulseaudio_threaded_mainloop, "PulseMainloop");
+    if (PULSEAUDIO_pa_threaded_mainloop_set_name) {
+        PULSEAUDIO_pa_threaded_mainloop_set_name(pulseaudio_threaded_mainloop, "PulseMainloop");
+    }
 
     if (PULSEAUDIO_pa_threaded_mainloop_start(pulseaudio_threaded_mainloop) < 0) {
         PULSEAUDIO_pa_threaded_mainloop_free(pulseaudio_threaded_mainloop);