Flavour labels were removed from globus library names in 2010.

CXX is the standard variable for this purpose.
CPP is usually used to indicate the C preprocessor.

- CC7 build jobs do not properly identify that the commit matches a tag
- Centos8 and Fedora jobs always identify when the commit matches a tag
- Gitlab-CI may run both a commit and a tag pipeline for the same commit. This creates the unwanted behavior of Centos8 and Fedora building a tag RPM in a commit pipeline

In the end, pass the branch variable from the pipeline to the build script, which now accepts a regex to identify tags

- Add print info function to build script
- Minor fixes to repo manager script

  - Build jobs for Fedora 33, Fedora 34 and Fedora Rawhide
  - Avoid failing the publish job if Fedora Rawhide RPMs do not exist
  - The "gfal2-repo-manager" script should recognize Fedora 35 and 36 as Rawhide versions

-v hangs, but -help doesn't give the version, use -V

Follow how myproxy does it, for instance, so via gsi.conf we can
revert the validation mechanism.