Upgrade Ceres library to current master which is current 1.5RC

This is helpful because it brings CHOLMOB-free ITERATIVE_SCHUR and
SCHUR_JACOBI which is really nice for new upcoming bundle adjustment.

If also includes all the local fixes we made locally.

There're lots of other improvements/fixed which are not currently
would be so much visible in Blender, but which opens doors for some
great improvements in future.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54839 954f8c5b-7b00-dc11-b283-0030488c597c