Add support for PROVE_TESTS and PROVE_FLAGS in MSVC scripts

These can be set in buildenv.pl or a "set" command within a Windows
terminal.  The MSVC script vcregress.pl parses the values available in
the environment to build the resulting prove commands, and the parsing
of PROVE_TESTS is able to handle name patterns in the same way as other
platforms.

Not specifying those environment values makes vcregress.pl fall back to
the previous default, with no extra flags for the prove command, and all
the tests run within t/.

Author: Michael Paquier
Reviewed-by: Juan José Santamaría Flecha, Julien Rouhaud
Discussion: https://postgr.es/m/YD9GigwHoL6lFY2y@paquier.xyz

doc/src/sgml/install-windows.sgml

@@ -496,6 +496,24 @@ $ENV{PERL5LIB}=$ENV{PERL5LIB} . ';c:\IPC-Run-0.94\lib';
     </varlistentry>
    </variablelist>
   </para>
+
+  <para>
+   The TAP tests run with <command>vcregress</command> support the
+   environment variables <varname>PROVE_TESTS</varname>, that is expanded
+   automatically using the name patterns given, and
+   <varname>PROVE_FLAGS</varname>. These can be set on a Windows terminal,
+   before running <command>vcregress</command>:
+<programlisting>
+set PROVE_FLAGS=--timer --jobs 2
+set PROVE_TESTS=t/020*.pl t/010*.pl
+</programlisting>
+   It is also possible to set up those parameters in
+   <filename>buildenv.pl</filename>:
+<programlisting>
+$ENV{PROVE_FLAGS}='--timer --jobs 2'
+$ENV{PROVE_TESTS}='t/020*.pl t/010*.pl'
+</programlisting>
+  </para>
  </sect2>
 
  </sect1>

src/tools/msvc/vcregress.pl

@@ -209,7 +209,21 @@ sub tap_check
 	my $dir = shift;
 	chdir $dir;
 
-	my @args = ("prove", @flags, glob("t/*.pl"));
+	# Fetch and adjust PROVE_TESTS, applying glob() to each element
+	# defined to build a list of all the tests matching patterns.
+	my $prove_tests_val   = $ENV{PROVE_TESTS} || "t/*.pl";
+	my @prove_tests_array = split(/\s+/, $prove_tests_val);
+	my @prove_tests       = ();
+	foreach (@prove_tests_array)
+	{
+		push(@prove_tests, glob($_));
+	}
+
+	# Fetch and adjust PROVE_FLAGS, handling multiple arguments.
+	my $prove_flags_val = $ENV{PROVE_FLAGS} || "";
+	my @prove_flags     = split(/\s+/, $prove_flags_val);
+
+	my @args = ("prove", @flags, @prove_tests, @prove_flags);
 
 	# adjust the environment for just this test
 	local %ENV = %ENV;