demoplayer: ignore suspend/resume requests when not initialized

This fixes a nasty interaction between the intro sequence and the
demoplayer introduced in 3ff6204. The cutscene tries to suspend the
demoplayer for its duration and then resume it later. When the
suspension counter hits 0, the demoplayer event handlers are installed
globally. And then AFTER that happens, the demoplayer is actually
initialized, resetting the suspension counter and installing the event
handlers AGAIN. When the demoplayer is then suspended (e.g. by starting
the actual demo playback), only one set of those handlers is removed,
which has the effect of the demoplayer remaining active even in-game.
Eventually, it tries to play a demo while a game is already running,
at which point all hell breaks loose.

Fix this by making suspend and resume no-ops until the demoplayer has
been properly initialized.

Fixes #371

src/replay/demoplayer.c

@@ -25,6 +25,7 @@ struct {
 	char **demo_files;
 	size_t num_demo_files;
 	int suspend_level;
+	bool initialized;
 } dplr;
 
 static bool demo_path_filter(const char *path) {
@@ -49,6 +50,10 @@ static inline int get_inter_wait_time(void) {
 }
 
 void demoplayer_init(void) {
+	if(dplr.initialized) {
+		return;
+	}
+
 	dplr.demo_files = vfs_dir_list_sorted(
 		DEMOPLAYER_DIR_PATH, &dplr.num_demo_files, vfs_dir_list_order_ascending, demo_path_filter
 	);
@@ -59,17 +64,24 @@ void demoplayer_init(void) {
 
 	dplr.next_demo_countdown = get_initial_wait_time();
 	dplr.suspend_level = 1;
+	dplr.initialized = true;
+
 	demoplayer_resume();
 }
 
 void demoplayer_shutdown(void) {
+	if(!dplr.initialized) {
+		return;
+	}
+
 	if(dplr.suspend_level == 0) {
 		demoplayer_suspend();
 	}
 
 	vfs_dir_list_free(dplr.demo_files, dplr.num_demo_files);
 	dplr.demo_files = NULL;
 	dplr.num_demo_files = 0;
+	dplr.initialized = false;
 }
 
 typedef struct DemoPlayerContext {
@@ -158,6 +170,11 @@ static bool demoplayer_activity_event(SDL_Event *evt, void *arg) {
 }
 
 void demoplayer_suspend(void) {
+	if(!dplr.initialized) {
+		log_debug("Not initialized");
+		return;
+	}
+
 	dplr.suspend_level++;
 	assert(dplr.suspend_level > 0);
 	log_debug("Suspend level is now %i", dplr.suspend_level);
@@ -173,6 +190,11 @@ void demoplayer_suspend(void) {
 }
 
 void demoplayer_resume(void) {
+	if(!dplr.initialized) {
+		log_debug("Not initialized");
+		return;
+	}
+
 	dplr.suspend_level--;
 	assert(dplr.suspend_level >= 0);
 	log_debug("Suspend level is now %i", dplr.suspend_level);