patch 8.0.0280: problem setting multi-byte environment var on MS-Windows

Problem:    On MS-Windows setting an environment variable with multi-byte
            strings does not work well.
Solution:   Use wputenv when possible. (Taro Muraoka, Ken Takata)

src/misc1.c

@@ -4453,9 +4453,6 @@ vim_setenv(char_u *name, char_u *val)
     {
 	sprintf((char *)envbuf, "%s=%s", name, val);
 	putenv((char *)envbuf);
-# ifdef libintl_putenv
-	libintl_putenv((char *)envbuf);
-# endif
     }
 #endif
 #ifdef FEAT_GETTEXT