pgsql: Teach chklocale.c how to extract encoding info from Windows

Log Message:
-----------
Teach chklocale.c how to extract encoding info from Windows locale
names. ITAGAKI Takahiro

Modified Files:
--------------
pgsql/src/port:
chklocale.c (r1.3 -> r1.4)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/port/chklocale.c?r1=1.3&r2=1.4)