Remove MSVC scripts

This commit removes all the scripts located in src/tools/msvc/ to build
PostgreSQL with Visual Studio on Windows, meson becoming the recommended
way to achieve that.  The scripts held some information that is still
relevant with meson, information kept and moved to better locations.
Comments that referred directly to the scripts are removed.

All the documentation still relevant that was in install-windows.sgml
has been moved to installation.sgml under a new subsection for Visual.
All the content specific to the scripts is removed.  Some adjustments
for the documentation are planned in a follow-up set of changes.

Author: Michael Paquier
Reviewed-by: Peter Eisentraut, Andres Freund
Discussion: https://postgr.es/m/ZQzp_VMJcerM1Cs_@paquier.xyz

config/perl.m4

@@ -53,10 +53,17 @@ AC_DEFUN([PGAC_CHECK_PERL_CONFIGS],
 # would be fatal to try to compile PL/Perl to a different libc ABI than core
 # Postgres uses.  The available information says that most symbols that affect
 # Perl's own ABI begin with letters, so it's almost sufficient to adopt -D
-# switches for symbols not beginning with underscore.  Some exceptions are the
-# Windows-specific -D_USE_32BIT_TIME_T and -D__MINGW_USE_VC2005_COMPAT; see
-# Mkvcbuild.pm for details.  We absorb the former when Perl reports it.  Perl
-# never reports the latter, and we don't attempt to deduce when it's needed.
+# switches for symbols not beginning with underscore.
+
+# Some exceptions are the Windows-specific -D_USE_32BIT_TIME_T and
+# -D__MINGW_USE_VC2005_COMPAT. To be exact, Windows offers several 32-bit ABIs.
+# Perl is sensitive to sizeof(time_t), one of the ABI dimensions.  PostgreSQL
+# doesn't support building with pre-MSVC-2005 compilers, but it does support
+# linking to Perl built with such a compiler.  MSVC-built Perl 5.13.4 and
+# later report -D_USE_32BIT_TIME_T in $Config{ccflags} if applicable, but
+# MinGW-built Perl never reports -D_USE_32BIT_TIME_T despite typically needing
+# it.
+#
 # Consequently, we don't support using MinGW to link to MSVC-built Perl.  As
 # of 2017, all supported ActivePerl and Strawberry Perl are MinGW-built.  If
 # that changes or an MSVC-built Perl distribution becomes prominent, we can

doc/src/sgml/filelist.sgml

@@ -39,7 +39,6 @@
 <!ENTITY installbin    SYSTEM "install-binaries.sgml">
 <!ENTITY installation  SYSTEM "installation.sgml">
 <!ENTITY targets-meson  SYSTEM "targets-meson.sgml">
-<!ENTITY installw      SYSTEM "install-windows.sgml">
 <!ENTITY maintenance   SYSTEM "maintenance.sgml">
 <!ENTITY manage-ag     SYSTEM "manage-ag.sgml">
 <!ENTITY monitoring    SYSTEM "monitoring.sgml">