Fix MSVC build for changes in zic.

zic now only needs zic.c, but I didn't realize knowledge about it was
hardwired into Mkvcbuild.pm.  Per buildfarm.

src/tools/msvc/Mkvcbuild.pm

@@ -375,8 +375,7 @@ sub mkvcbuild
 	$pgrestore->AddLibrary('ws2_32.lib');
 
 	my $zic = $solution->AddProject('zic', 'exe', 'utils');
-	$zic->AddFiles('src/timezone', 'zic.c', 'ialloc.c', 'scheck.c',
-		'localtime.c');
+	$zic->AddFiles('src/timezone', 'zic.c');
 	$zic->AddDirResourceFile('src/timezone');
 	$zic->AddReference($libpgcommon, $libpgport);