Turn most vc build scripts into modules instead of scripts, and just have

skeleton scripts calling them. To make it easier for the buildfarm
(or other "outside callers") to use these modules directly.

Per suggestion from Andrew Dunstan.

src/tools/msvc/Solution.pm

@@ -3,6 +3,8 @@ use Carp;
 use strict;
 use warnings;
 
+use Genbki;
+
 sub new
 {
     my $junk = shift;
@@ -266,8 +268,11 @@ EOF
         if (IsNewer('src/backend/catalog/postgres.bki', "src/include/catalog/$bki"))
         {
             print "Generating postgres.bki...\n";
-            system("perl src/tools/msvc/genbki.pl $self->{majorver} src/backend/catalog/postgres "
-                  . join(' src/include/catalog/',@allbki));
+            Genbki::genbki(
+                $self->{majorver},
+                "src/backend/catalog/postgres",
+                split(/ /,join(' src/include/catalog/',@allbki))
+            );
             last;
         }
     }