Recommit r356738 "[llvm-objcopy] - Implement replaceSectionReferences for GroupSection class."

Fix: r356853 + set AddressAlign to 4 in 
Inputs/compress-debug-sections.yaml for the new group section introduced.

Original commit message:

Currently, llvm-objcopy incorrectly handles compression and decompression of the
sections from COMDAT groups, because we do not implement the
replaceSectionReferences for this type of the sections.

The patch does that.

Differential revision: https://reviews.llvm.org/D59638

llvm-svn: 356856