libobs: Store string copies in properties

Individual property objects would store pointers to strings rather than
copies of the strings and assume that memory would continue to exist, so
instead just duplicate the strings.

libobs/obs-properties.c

@@ -143,9 +143,9 @@ static inline void frame_rate_data_free(struct frame_rate_data *data)
 struct obs_properties;
 
 struct obs_property {
-	const char              *name;
-	const char              *desc;
-	const char              *long_desc;
+	char                    *name;
+	char                    *desc;
+	char                    *long_desc;
 	enum obs_property_type  type;
 	bool                    visible;
 	bool                    enabled;
@@ -222,6 +222,9 @@ static void obs_property_destroy(struct obs_property *property)
 	else if (property->type == OBS_PROPERTY_FRAME_RATE)
 		frame_rate_data_free(get_property_data(property));
 
+	bfree(property->name);
+	bfree(property->desc);
+	bfree(property->long_desc);
 	bfree(property);
 }
 
@@ -323,8 +326,8 @@ static inline struct obs_property *new_prop(struct obs_properties *props,
 	p->enabled = true;
 	p->visible = true;
 	p->type    = type;
-	p->name    = name;
-	p->desc    = desc;
+	p->name    = bstrdup(name);
+	p->desc    = bstrdup(desc);
 	propertes_add(props, p);
 
 	return p;
@@ -604,12 +607,22 @@ void obs_property_set_enabled(obs_property_t *p, bool enabled)
 
 void obs_property_set_description(obs_property_t *p, const char *description)
 {
-	if (p) p->desc = description;
+	if (p) {
+		bfree(p->desc);
+		p->desc = description && *description
+			? bstrdup(description)
+			: NULL;
+	}
 }
 
 void obs_property_set_long_description(obs_property_t *p, const char *long_desc)
 {
-	if (p) p->long_desc = long_desc;
+	if (p) {
+		bfree(p->long_desc);
+		p->long_desc = long_desc && *long_desc
+			? bstrdup(long_desc)
+			: NULL;
+	}
 }
 
 const char *obs_property_name(obs_property_t *p)