Update to 6.24.02
ROOT now uses llvm/clang version 9 (updated from version 5)
No longer exclude arch s390x (better supported in llvm/clang 9)
Drop patches accepted upstream or previously backported
Backport some fixes that make more tests work
New subpackages: python{2,3}-distrdf, root-roofit-batchcompute
Require js-jsroot >= 6