Draft: Compress debug sections
When separating the debug sections from libraries and executables, compress them if possible. This works with the GNU/system objcopy but not with llvm-objcopy, so it depends on the CMAKE_COMPILER_ID.
The default is zlib compression, but once CentOS 7 is gone this can be changed to --compress-debug-sections=zstd and one gains a bit more.
The gains seen in TDAQ were about a factor 2-3 reduction in size of the debug information. In total the binary part of a full TDAQ build went from 4.3 GByte to 1.6 GByte (plus a few hundred MByte of arch independent stuff).
So far there were no drawbacks seen, gdb etc. works, although it obviously has to decompress the information during the debug session.
Tagging @akraszna , do you think there are any other drawbacks ?
I will put a few numbers for athena libraries here once I figure out how to use my private version without building all externals.