* time/asctime.c (asctime_internal): New function, derived from
asctime_r. Takes additional parameter which is the buffer length.
Use snprintf instead sprintf, if it overflows, fail.
(asctime_r): Call asctime_internal with 26 as buffer length.
(asctime): Call asctime_internal with length of internal buffer.
* time/Makefile (tests): Add bug-asctime_r.
* time/bug-asctime_r.c: New file.