Description:
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After the recent tzdb format change, then a simple call to mktime now crashes.

Looking into it a tiny bit shows that the whole magic happens in read_location() (ext/date/lib/parse_tz.c), buffer[2] which is the length of the comments is passed through the timelib_conv_int() macro that then causes the number to be negative, thrus making malloc fail

I did not test against the 5.x versions that was also affected by the db update, but I guess the same problem persists there.

Test script:
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php -r "mktime();" <- No crash

php -d date.timezone=CET -r "mktime();" <- Crash