Add chklocale.c to msvc build

Petr Jelinek wrote:

Hi,
attached patch adds chklocale.c to pgportfiles in Mkvcbuild perl module
(not really worth the .diff :))
This fixes MSVC build (see buildfarm errors with unresolved reference
for _pg_get_encoding_from_locale).

Similar patch applied. I put the chklocale.c file in "pseudo alphabtical
order". I say pseudo because I think I originally planned to have them
alphabetically, but I've obviously broken that many times before :-)

//Magnus