Get correct lcb version burned in when building

When we build, we pull the LCB source from packages.couchbase.com, using the LCB_TAG supplied by the cbuild_cfg.json. When we then build, the cmake files in LCB try to get the version (most recent tag, plus the current SHA) from git. That of course doesn't work, as we didn't pull a git repo in for LCB. Instead, we get the python version and SHA.

We could just specify -DLCB_SKIP_GIT_VERSION=ON and -DLCB_VERSION=<whatever> when building. If one specifies a tag, this works fine, but the logged LCB version will have the default 0xdeadbeef for the SHA. Oddly enough, same for specifying a SHA in LCB_TAG. Unsure how that works - should be looked into.

So - perhaps we should do this? Or maybe investigate how to get the SHA reporting in the LCB logging as well?