* Patch the soci unsigned-types.h file. If no changes are made, delete
the patched file and exit. If there are changes, backup the original
and replace it with the patched file.
* Fixes#3885
Patch Rocksdb only once:
* The repeated patches do not appear to affect build times, but avoiding
unnecessary copies is good for its own sake.
* update EP and find package requirements
* minor protobuf/libarchive build fixes
* change travis release builds to nounity to
ameliorate vm memory exhaustion.
FIXES: #3223, #3232
* use tagged containers for pkg build
* update build images
* continue to build container images in pipeline, but allow
failure (non-block)
* limit travis macos cache
* add vs2019 windows to travis
* remove xcode 9 travis build
* remove clang5/6 from CI and update min version of Clang required in
cmake
* break windows CI build into stages to reduce timeouts
* update datelib
* add if condition to travis builds to allow commit message to limit
builds by platform
