CI failes because of svn export error in cpt.py

[Simeon Ehrig]

The current CI jobs fails, because the command svn export http://llvm.org/svn/llvm-project/llvm/branches/release_50/utils/FileCheck FileCheck in the cpt.py script fails: https://github.com/root-project/cling/runs/1681513196

I think, this happens, because the llvm project moved from svn to git and at some point, they deactivate the svn repository.

[Simeon Ehrig]

ping @reikdas

[Pratyush Das]

Fixed in master.