Fix various memory leaks

Found with clang-tidy

sway/commands.c

@@ -198,9 +198,6 @@ static void set_config_node(struct sway_node *node) {
 
 list_t *execute_command(char *_exec, struct sway_seat *seat,
 		struct sway_container *con) {
-	list_t *res_list = create_list();
-	char *exec = strdup(_exec);
-	char *head = exec;
 	char *cmd;
 	char matched_delim = ';';
 	list_t *views = NULL;
@@ -213,9 +210,16 @@ list_t *execute_command(char *_exec, struct sway_seat *seat,
 		}
 	}
 
+	char *exec = strdup(_exec);
+	char *head = exec;
+	list_t *res_list = create_list();
+
+	if (!res_list || !exec) {
+		return NULL;
+	}
+
 	config->handler_context.seat = seat;
 
-	head = exec;
 	do {
 		for (; isspace(*head); ++head) {}
 		// Extract criteria (valid for this command list only).

sway/config.c

@@ -687,8 +687,10 @@ static ssize_t getline_with_cont(char **lineptr, size_t *line_size, FILE *file,
 		nread += next_nread - 2;
 		if ((ssize_t) *line_size < nread + 1) {
 			*line_size = nread + 1;
+			char *old_ptr = *lineptr;
 			*lineptr = realloc(*lineptr, *line_size);
 			if (!*lineptr) {
+				free(old_ptr);
 				nread = -1;
 				break;
 			}

sway/main.c

@@ -259,6 +259,7 @@ int main(int argc, char **argv) {
 			exit(EXIT_SUCCESS);
 			break;
 		case 'c': // config
+			free(config_path);
 			config_path = strdup(optarg);
 			break;
 		case 'C': // validate