change max number of PDF sets for lhapdf full memory variant
update photos++
Use thepeg from cms-externals and update, update herwigpp.

This PR overrides #881.
Merge pull request #931 from degano/thepeg_herwigpp_72X

Use thepeg from cms-externals and update, update herwigpp.
Merge pull request #918 from inugent/photospp355_7_2_X

update photos++
Merge pull request #837 from mkirsano/lhapdf_numsets

change max number of PDF sets for lhapdf full memory variant
cms-common: fix cmsarch for fc19_aarch64 cmsos

cmsos script returns fc19_aarch64 or fc19_armv7hl, yet cmsarch
script expected an additional underscore after cmsos. Resolve it
by checking exact match to cmsos.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #935 from davidlt/fix-cms-common-aarch64

cms-common: fix cmsarch for fc19_aarch64 cmsos
Update libunwind.

- Update to the HEAD, move to use cms-externals.
- Pick up ARM64 fast backtrace patches from @fillexen.
- Add autotools buildrequires and do autoreconf.
Merge pull request #936 from ktf/new-libunwind

Update libunwind.
Merge remote-tracking branch 'origin/IB/CMSSW_7_2_X/stable' into IB/CMSSW_7_0_X/stable