Blind attempt at fixing Windows build

Broken since fe33a196.

src/tools/msvc/Solution.pm

@@ -276,7 +276,7 @@ sub GenerateFiles
 		|| IsNewer('fmgr-stamp', '../../../src/include/access/transam.h'))
 	{
 		system(
-			"perl -I ../catalog Gen_fmgrtab.pl -I../../../src/include/ $pg_proc_dat"
+			"perl -I ../catalog Gen_fmgrtab.pl --include-path ../../../src/include/ $pg_proc_dat"
 		);
 		open(my $f, '>', 'fmgr-stamp')
 		  || confess "Could not touch fmgr-stamp";
@@ -527,7 +527,7 @@ EOF
 	{
 		chdir('src/backend/catalog');
 		my $bki_srcs = join(' ../../../src/include/catalog/', @bki_srcs);
-		system("perl genbki.pl  -I../../../src/include/ --set-version=$self->{majorver} $bki_srcs");
+		system("perl genbki.pl --include-path ../../../src/include/ --set-version=$self->{majorver} $bki_srcs");
 		open(my $f, '>', 'bki-stamp')
 		  || confess "Could not touch bki-stamp";
 		close($f);