It is not too rare that '\0' chars appear in /var/log/messages. I saw a
real-life case where kerneloops would show a popup with the same old oops
after every login. It turned out that there were NUL chars in the log which
prevented kerneloops from seeing its marker, so it always treated the old oops
in the log as new.
This patch fixes it by always going through the whole known length of the
buffer (not stopping on NUL chars) and using less string-oriented functions in
fill_lineinfo().

* backport of 14e769d7093179943015ff88d0d3bdd65b2947f7
* Author: Michal Schmidt <mschmidt@redhat.com>

The linepointer array is huge!:
    linepointer = calloc(buflen+1, sizeof(char*));
buflen can be as much as 32 MB, that makes it allocate 32M*8 = 256M on x86_64.

Fix it by growing the allocation dynamically as we find interesting lines in
the log.

Because of MAX/MIN confusion, the buffer size was always at least 32 MB,
instead of at most 32 MB as intended.