Log Message:
Update to 1.7.8:

Adam Jackson (5):
      Remove miInitializeBackingStore()
      Use own thunk function instead of vgaHW*Weak
      Fix build against xserver 1.17
      Fix a typo
      Remove dependency on xf86PciInfo.h

Julien Cristau (5):
      Fix shadow compiler warning
      Fix BlockHandler declaration
      Fix SwitchMode and AdjustFrame hooks
      Fix a couple const-ness warnings
      Bump to 1.7.8