Externals Update (CentOS 7 Fixes), 21.0-mc16d branch (2020.10.05.)

This is a sibling of !36972 (merged).

Updated all projects to atlasexternals-1.0.27.2 to fix the build issues of Athena-21.0-mc16d on x86_64-slc6-gcc62-opt and x86_64-centos7-gcc62-opt, as described in ATLINFR-3741.

The full list of changes wrt. atlasexternals-1.0.27 is (atlasexternals@1.0.27...1.0.27.2):

• Updated the Simage build to succeed on CentOS 7 (cherry-picking an ancient fix from @rbianchi);
• Updated the UUID external handling of AtlasLCG, AthenaExternals, AthDerivationExternals and yampl, to be compatible with CentOS 7 (cherry-picking fixes made for the 21.0 branch recently);
  • Including the update of yampl from version 4a91d89 to 46f7a48;
• Updated atlas_setup_cpack() to create a functional setup for building RPMs with the latest OS updates.

As in !36853 (merged), I had to disable the build of FTKStandaloneMonitoring. (As the build of that package on x86_64-centos7-gcc62-opt is never going to succeed in this branch.)

As discussed in ATLINFR-3741, we will need a build of dqm-common-01-02-00 for x86_64-centos7-gcc62-opt before the CentOS 7 nightly would succeed. But this update should be useful for the SLC6 nightly at least. So we can push it in before the new dqm-common build would be ready...