initctl: fix file descriptor leak causing 'initctl top' to crash

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

src/cgutil.c

@@ -102,6 +102,7 @@ char *pid_cmdline(int pid)
 			buf[i] = ' ';
 	}
 
+	fclose(fp);
 	return buf;
 }