* libc/include/sys/config.h: define __IMPORT appropriately

* libc/include/sys/config.h: define __IMPORT appropriately
* libc/include/ctype.h (_ctype_): use __IMPORT
* libc/include/math.h (__infinity, signam, _LIB_VERSION): ditto
* libc/include/math.h (__mb_cur_max): ditto
* libc/include/time.h (_timezone, _daylight, _tzname): ditto
* libc/include/unctrl.h (__unctrl, __unctrllen): ditto
* libc/include/errno.h (_sys_errlist, _sys_nerr): ditto
* libc/include/unistd.h (environ): ditto