On SIGCHLD, check to make sure the terminated process is not the XWayland process before reaping it, allowing wlroots to waitpid() for it successfully.
Fixes #177.
HH5I4HSPYNDRQHIOTASMU5BGFD754OUI4ZGRZQHUE5SM6OTJTEWQC while (0 < waitpid(-1, NULL, WNOHANG));
/* WNOWAIT leaves the child in a waitable state, in case this is the* XWayland process*/while (!waitid(P_ALL, 0, &in, WEXITED|WNOHANG|WNOWAIT) && in.si_pid&& in.si_pid != xwayland->server->pid)waitpid(in.si_pid, NULL, 0);