Change library SONAMEs to include minor version

[jyknight]

As suggested in #75743 and https://discourse.llvm.org/t/rfc-name-the-first-release-from-a-branch-n-1-0-instead-of-n-0-0/75384 there is a desire to switch from just the major version (e.g. "18") to instead use major+minor (e.g. "18.0" or "18.1").