Best-guess attempt at fixing MSVC build for 68ab8e8b.

pgbench now needs to use src/bin/psql/psqlscan.l, but it's not very clear
how to fit that into the MSVC build system.  If this doesn't work I'm going
to need some help from somebody who actually understands those scripts ...

src/tools/msvc/Mkvcbuild.pm

@@ -62,11 +62,13 @@ my $frontend_extralibs = {
 	'psql'       => ['ws2_32.lib'] };
 my $frontend_extraincludes = {
 	'initdb' => ['src/timezone'],
-	'psql'   => [ 'src/bin/pg_dump', 'src/backend' ] };
+	'psql'   => [ 'src/bin/pg_dump', 'src/backend' ],
+	'pgbench' => [ 'src/bin/psql' ] };
 my $frontend_extrasource = {
 	'psql' => ['src/bin/psql/psqlscan.l', 'src/bin/psql/psqlscanslash.l'],
 	'pgbench' =>
-	  [ 'src/bin/pgbench/exprscan.l', 'src/bin/pgbench/exprparse.y' ], };
+	  [ 'src/bin/pgbench/exprscan.l', 'src/bin/pgbench/exprparse.y',
+	    'src/bin/psql/psqlscan.l' ] };
 my @frontend_excludes = (
 	'pgevent',     'pg_basebackup', 'pg_rewind', 'pg_dump',
 	'pg_xlogdump', 'scripts');