pythia8: do not use -Qunused-arguments on GCC

By default Pythia8 assumes that on Darwin LLVM/Clang will be used and
-Qunused-arguments option is passed. Such option is not supported
by GCC. Modify configure script to check for Clang.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
update to pythia 8.200 (official release)
pythia8: do not use -Qunused-arguments on GCC

By default Pythia8 assumes that on Darwin LLVM/Clang will be used and
-Qunused-arguments option is passed. Such option is not supported
by GCC. Modify configure script to check for Clang.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
update to pythia 8.200 (official release)
Merge pull request #1117 from bendavid/py8200final_72x

Pythia 8.200 final (72x)
Merge pull request #1118 from bendavid/py8200final_71x

Pythia 8.200 final (71x)
Update root to the HEAD.
Merge pull request #1119 from degano/root_53418_72XStable

Update root to the HEAD.
Update to include "Implement Clone for histograms".

https://github.com/cms-sw/root/commit/0e440ee5f066ea63115eb843366bd23d5c40fe42.
Merge pull request #1127 from degano/root_53418_73XStable

Update to include "Implement Clone for histograms".
backport of dxr tools in to 73X stable
Merge pull request #1131 from smuzaffar/IB/CMSSW_7_3_X/stable

backport of dxr tools in to 73X stable
Merge pull request #1134 from smuzaffar/IB/CMSSW_7_3_X/root6

fixed the PYTHIA8DATA path for pythia8 200
Move to cms-sw/root@04ffc3
Merge pull request #1136 from ktf/revert-chris-changes

Move to cms-sw/root@04ffc3
Update root and roofit to the new head.

https://github.com/cms-sw/root/commit/07f1df4138b9764c6176e6c2d57a6ace91cf2c23.
Merge pull request #1137 from degano/root_53418_updateHead

Update root and roofit to the new head.
Move to the latest root.
Merge pull request #1138 from ktf/new-root6

Move to the latest root.
Merge remote branch 'origin/IB/CMSSW_7_3_X/stable' into IB/CMSSW_7_0_X/stable