Removed the extra ntree->update flag check in lib_verify_nodetree in readfile.c. This is unnecessary as the update flag will be checked internally in ntreeUpdateTree anyway, except for the generic bNodeTreeType->update callback (it could even be harmful by preventing necessary updates that don't use the ntree->update flag). Executing this once after loading a node tree is a useful feature for pynodes, so they can do initial verification.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56055 954f8c5b-7b00-dc11-b283-0030488c597c