localeinit.c: cp on cygwin

* localeinit.c (SIZEOF_CP_NAME, CP_FORMAT): needed on cygwin too.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44708 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

localeinit.c

@@ -19,7 +19,7 @@
 #include <langinfo.h>
 #endif
 
-#if defined _WIN32
+#if defined _WIN32 || defined __CYGWIN__
 #define SIZEOF_CP_NAME ((sizeof(UINT) * 8 / 3) + 4)
 #define CP_FORMAT(buf, codepage) snprintf(buf, sizeof(buf), "CP%u", (codepage))
 #endif