tst-timezone dumps core

[Zack Weinberg]

For awhile now tst-timezone dumps core in __tzfile_read, in this loop:

277       for (i = 0; i < num_types; ++i)
278         __tzname[types[i].isdst] = __tzstring (&zone_names[types[i].idx]);

num_types is absurdly large, so it runs off the end of the array.
Probably the bug is in decode().

zw