patch 8.0.0175: setting language on MS-Windows does not always work

Problem:    Setting language in gvim on MS-Windows does not work when
            libintl.dll is dynamically linked with msvcrt.dll.
Solution:   Use putenv() from libintl as well. (Ken Takata, closes #1082)

src/misc1.c

@@ -4455,6 +4455,9 @@ 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