src: stop using O_DIRECTORY in resctrl

The O_DIRECTORY flag causes open() to return an error
if the filename is a directory. There's no obvious
reason why resctrl needs to use this, while the rest of
libvirt code does not. Removing it avoids build issues
on platforms where O_DIRECTORY is not defined, once we
remove GNULIB.
Reviewed-by: NPavel Hrdina <phrdina@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/util/virresctrl.c

@@ -455,7 +455,7 @@ VIR_ONCE_GLOBAL_INIT(virResctrl);
 static int
 virResctrlLockWrite(void)
 {
-    int fd = open(SYSFS_RESCTRL_PATH, O_DIRECTORY | O_CLOEXEC);
+    int fd = open(SYSFS_RESCTRL_PATH, O_RDWR | O_CLOEXEC);
 
     if (fd < 0) {
         virReportSystemError(errno, "%s", _("Cannot open resctrl"));