Meson is a new build system that offers simpler syntax and superior performance to autoconf/make. In addition, Windows is supported natively.
The Meson build appears complete, but currently is used only for auto-generation of code and the host build of pgbackrest. Some container upgrades will be required before Meson can be used for container builds.
Also patch the Debian package to force autoconf/make rather than Meson.
Since CentOS 8 will be EOL at the end of the year it makes sense to do this now. The centos:8 image is still used in documentation.xml because changes there require manual testing, which will need to be done at a later date. The changes are not user-facing, however, and can be done at any time.
Also update CentOS references to RHEL since that is what we are emulating for testing purposes.
These tests run in a container without permissions to mount tempfs, so add an option to ci.pl to not create tempfs. Also add some packages not in the base image.
Parse enough of config.yaml to auto-generate config.auto.h and config.auto.c.
This commit implements most of the infrastructure needed to migrate the rest of the build code to C, but each set of auto-generated files will present its own challenges.
The build is now dependent on libyaml. At this point there is no need for a hard requirement, but that will come soon so it seems better to add the dependency now.
The CentOS 7 documentation test relies on PostgreSQL 9.5 which has been removed from the yum.p.o repository package. Switch the test to CentOS 8 to fix the immediate issue, but a decision on the PostgreSQL 9.5 documentation will need to be made before the next release.
YAML::XS requires libyaml so it not as portable as pure Perl versions of YAML.
Instead of using YAML:PP just use the general YAML::Any module which uses whatever is installed. We are not concerned about performance for YAML so whatever works is fine.
Testing on Travis-CI has been getting slower (from ~18 minutes to 3-6 hours) and the travis-ci.org service will be terminated at the end of the year. Moving to travis-ci.com is an option but the quotas are too low for our purposes.
Instead use Github Actions, which does not currently have quotas, and runs our current tests with just a few tweaks.
This still leaves multi-architecture tests on Travis-CI but we may be able to run those and stay within the new quotas.
Also fix a minor bug in restoreTest.c exposed by Github Actions using a different name for the user and group.
