procname_kill(): Fix possible resource leak and let's use opendir() errno

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

helpers.c

@@ -270,12 +270,15 @@ int procname_kill(char *name, int signo)
 	DIR *dir;
 	struct dirent *entry;
 
-	dir = opendir("/proc");
-	if (!dir || !name) {
+	if (!name) {
 		errno = EINVAL;
 		return 0;
 	}
 
+	dir = opendir("/proc");
+	if (!dir)
+		return 0;
+
 	while ((entry = readdir(dir)) != NULL) {
 		/* Skip non-process entries in /proc */
 		if (!isdigit(*entry->d_name))