X server hangs with black screen after applying security updates in Red Hat Enterprise Linux 6.

Issue

• After security updates, system is no longer able to start X server.
• It seems X server is not starting, getting blank screen after system restart.
• Running startx, or changing runlevel by using init 5 giving errors:

Loading extension GLX
/usr/bin/X: symbol lookup error: /usr/lib64/xorg/modules/libvgahw.so: undefined symbol: pci_device_map_legacy
giving up.

xinit:  Connection refused (errno 111):  unable to connect to X server
xinit:  No such process (errno 3):  Server error.

Or

/usr/bin/X: symbol lookup error: /usr/bin/X: undefined symbol: pci_legacy_open_io
giving up.
xinit:  No such file or directory (errno 2):  unable to connect to X server
xinit:  No such process (errno 3):  Server error.

Error: unable to open display / GUI

Or

Loading extension GLX
  /usr/bin/X: symbol lookup error: /usr/lib64/xorg/modules/libint10.so: undefined symbol: pci_device_map_legacy

• Cannot display login page via console after recent system update.