pgsql: meson: Increase minimum version to 0.57.2

meson: Increase minimum version to 0.57.2

The previous minimum was to maintain support for Python 3.5, but we
now require Python 3.6 anyway (commit 45363fca637), so that reason is
obsolete. A small raise to Meson 0.57 allows getting rid of a fair
amount of version conditionals and silences some future-deprecated
warnings.

With the version bump, the following deprecation warnings appeared and
are fixed:

WARNING: Project targets '>=0.57' but uses feature deprecated since '0.55.0': ExternalProgram.path. use ExternalProgram.full_path() instead
WARNING: Project targets '>=0.57' but uses feature deprecated since '0.56.0': meson.build_root. use meson.project_build_root() or meson.global_build_root() instead.

It turns out that meson 0.57.0 and 0.57.1 are buggy for our use, so
the minimum is actually set to 0.57.2. This is specific to this
version series; in the future we won't necessarily need to be this
precise.

Reviewed-by: Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
Reviewed-by: Andres Freund <andres(at)anarazel(dot)de>
Discussion: https://www.postgresql.org/message-id/flat/42e13eb0-862a-441e-8d84-4f0fd5f6def0%40eisentraut.org

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/f039c2244110a55e966e8538b6be8bf83458a0fb

Modified Files
--------------
contrib/basebackup_to_shell/meson.build | 4 +-
contrib/dblink/meson.build | 2 +-
contrib/postgres_fdw/meson.build | 2 +-
doc/src/sgml/installation.sgml | 2 +-
meson.build | 244 ++++++++++++--------------
src/backend/jit/llvm/meson.build | 2 +-
src/bin/pg_basebackup/meson.build | 6 +-
src/bin/pg_dump/meson.build | 6 +-
src/bin/pg_verifybackup/meson.build | 8 +-
src/include/nodes/meson.build | 2 +-
src/include/pch/meson.build | 6 +-
src/makefiles/meson.build | 10 +-
src/pl/plperl/meson.build | 2 +-
src/test/modules/injection_points/meson.build | 2 +-
src/test/modules/oauth_validator/meson.build | 2 +-
src/test/ssl/meson.build | 2 +-
16 files changed, 144 insertions(+), 158 deletions(-)