Meson far from ready on Windows

Hi

Further to my previous report [1] about zlib detection not working with
Meson on Windows, I found it's similarly or entirely broken for the
majority of other dependencies, none of which are tested on the buildfarm
as far as I can see.

For convenience, I've put together a number of Github actions [2] that show
how to build the various dependencies on Windows, in the most
standard/recommended way I can find for each. Another action combines these
into a single downloadable archive that people can test with, and another
one uses that archive to build PostgreSQL 12 through 16, all successfully.

You can see build logs, and download the various builds/artefacts from the
Github Workflow pages.

My next task was to extend that to support PostgreSQL 17 and beyond, which
is where I started to run into problems. I've attempted builds using Meson
with each of the dependencies defined in the old-style config.pl, both with
and without modifying the INCLUDE/LIBS envvars to include the directories
for the dependencies (as was found to work in the previous discussion re
zlib):

Will not successfully configure at all:

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dgssapi=enabled
build-gssapi

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dicu=enabled
build-icu

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dlibxml=enabled
build-libxml

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dlz4=enabled
build-lz4

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dnls=enabled
build-nls

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Duuid=ossp
build-uuid

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dzstd=enabled
build-zstd

Configured with modified LIBS/INCLUDE:

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dlibxslt=enabled
build-libxslt

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dssl=openssl
build-openssl

meson setup --auto-features=disabled
-Dextra_include_dirs=C:\build64\include
-Dextra_lib_dirs=C:\build64\lib;C:\build64\lib64 --wipe -Dzlib=enabled
build-zlib

I think it's important to note that Meson largely seems to want to use
pkgconfig and cmake to find dependencies. pkgconfig isn't really a thing on
Windows (it is available, but isn't commonly used), and even cmake would
typically rely on finding things in either known installation directories
or through lib/include vars. There really aren't standard directories like
/usr/lib or /usr/include as we find on unixes, or pkgconfig files for
everything.

For the EDB installers, the team has hand-crafted pkgconfig files for
everything, which is clearly not a proper solution.

I can provide logs and run tests if anyone wants me to do so. Testing so
far has been with the Ninja backend, in a VS2022 x86_64 native environment.

[1]
https://www.postgresql.org/message-id/CA+OCxozrPZx57ue8rmhq6CD1Jic5uqKh80=vTpZurSKESn-dkw@mail.gmail.com
[2] https://github.com/dpage/winpgbuild/actions

-- 
Dave Page
pgAdmin: https://www.pgadmin.org
PostgreSQL: https://www.postgresql.org
EDB: https://www.enterprisedb.com