libgui: Make computeTextureMatrix non-static

In ConsumerBase, computeTextureMatrix tries to access a member
variable when verbose logging is enabled. This change makes the method
non-static since there's no real reason for it to be static.

Bug 944874
Bug 1333245

Change-Id: I5db1943612aa9dc3a42cebefbd14e54ae37bfbbe
Reviewed-on: http://git-master/r/199743
(cherry picked from commit 1397c71861916f48d552c60d5a790775336e262d)
Reviewed-on: http://git-master/r/259046
Reviewed-by: Srikumar Bonda <sbonda@nvidia.com>
Tested-by: Srikumar Bonda <sbonda@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Dan Willemsen <dwillemsen@nvidia.com>