Update haproxy to 1.5.2. Introduce support for OpenSSL, PCRE and Zlib.

1.5.2
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Two extra important issues were discovered since 1.5.1 which were fixed
in 1.5.2. The first one can cause some sample fetch combinations to fail
together in a same expression, and one artificial case (but totally
useless) may even crash the process. The second one is an incomplete
fix in 1.5-dev23 for the request body forwarding. Hash-based balancing
algorithms and http-send-name-header may fail if a request contains
a body which starts to be forwarded before the contents are used.
A few other bugs were fixed, and the max syslog line length is now
configurable per logger.

1.5.1
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Version 1.5.1 fixes a few bugs from 1.5.0 among which a really annoying
one which can cause some file descriptor leak when dealing with clients
which disappear from the net, resulting in the impossibility to accept
new connections after some time.

1.5.0
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1.5 expands 1.4 with many new features and performance improvements,
including native SSL support on both sides with SNI/NPN/ALPN and OCSP
stapling, IPv6 and UNIX sockets are supported everywhere, full HTTP
keep-alive for better support of NTLM and improved efficiency in
static farms, HTTP/1.1 compression (deflate, gzip) to save bandwidth,
PROXY protocol versions 1 and 2 on both sides, data sampling on
everything in request or response, including payload, ACLs can use
any matching method with any input sample maps and dynamic ACLs
updatable from the CLI stick-tables support counters to track
activity on any input sample custom format for logs, unique-id,
header rewriting, and redirects, improved health checks (SSL,
scripted TCP, check agent, ...), much more scalable configuration
supports hundreds of thousands of backends and certificates without
sweating.

Full changelog for the 1.5 branch:

http://www.haproxy.org/download/1.5/src/CHANGELOG