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now require Python 3.6 anyway (commit 45363fca637), so that reason is
obsolete.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@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.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(-)