Bugfix: Use ev_loop_new instead of ev_default_loop because the latter one blocks SIGCHLD (Thanks Ciprian)

SIGCHLD was inherited to child processes started by i3 and not
all of them unblocked it (shells generally did, though), leading to
zombie processes.

src/mainx.c

@@ -266,7 +266,7 @@ int main(int argc, char *argv[], char *env[]) {
         }
 
         /* Initialize event loop using libev */
-        struct ev_loop *loop = ev_default_loop(0);
+        struct ev_loop *loop = ev_loop_new(0);
         if (loop == NULL)
                 die("Could not initialize libev. Bad LIBEV_FLAGS?\n");