Some of the more generically named functions are at risk of colliding
with functions defined in other libraries. To mitigate that risk,
prefix with "repmgr_", unless the name already has some reference
to repmgr.
This requires an extension version bump.
RM20471.
Until now the extension version has always moved in lock-step
with the binary version, but that doesn't always need to be
the case, so make it possible to have an extension version
which does not match the binary version.
Previous initial "major" releases were two-element only (e.g. 4.4);
beginning from repmgr 5 we want to ensure all version numbers have
three elements, for general consistency, including the generation
of package names.
Due to [insert reason here], in the Debian package build process (and
only there), when building frontend code PG_VERSION_NUM appears to be
from the newest libpq-dev version installed, and does not necessarily
match the version of the server the code is being built against.
To work around this distribution-specific package build issue, we'll
define our own substitution variable which is taken from the value
provided in Makefile.global.
Note that the next release is intended to be 5.0 to coincide with the
release of PostgreSQL 12; 4.5 is currently a placeholder in case we
need to push out a feature release before then.
repmgr requires that the same "major version" (e.g. 4.3) is present
on all nodes, otherwise - particularly in the case of repmgrd - it's
highly likely things won't work as expected.
Implements part of GitHub #515.
