Add test cases for CVE-2005-1849 and CVE-2005-2096

Add test cases for CVE-2005-1849 and CVE-2005-2096

CVE-2005-1849[0] is an overflow of a fixed size buffer defined in
inftrees.h

CVE-2005-2096[1] is an overflow caused by insufficient input
validation of code trees[2].

This makes sure we don't accidentally reintroduce them.

zlib-1.2.1 was download and fuzz tested using AFL[3].  The crashing
cases were discovered. A patch for 1849 was then applied, and used to
determine which cases hit only that bug, and which ones hit 2096.

[0] http://seclists.org/bugtraq/2005/Jul/451
[1] http://seclists.org/bugtraq/2005/Jul/53
[2] https://bug299445.bugzilla.mozilla.org/attachment.cgi?id=188021
[3] http://lcamtuf.coredump.cx/afl/

Signed-off-by: Daniel Axtens <dja@axtens.net>