Update rabbitmq-c to 0.5.2.

Changes in 0.5.2

fcdf0f8 Autoconf: check for htonll as declaration in a header file
5790ec7 SSL: correctly report hostname verification errors.
d60c28c Build: disable OpenSSL deprecation warnings on OSX
072191a Lib: include platform, version and copyright in AMQP handshake
8b448c6 Examples: print message body in amqp[s]_listen[q] examples
7188e5d Tools: Add flag to set prefetch for amqp-consume tool

Changes in 0.5.1

a566929 SSL: Add support for wildcards in hostname verification (Mike Steinert)
a78aa8a Lib: Use poll(2) instead of select(2) for timeouts on sockets.
357bdb3 Lib: support for specifying frame and decoding pool sizes. (Mike Stitt)
8956003 Lib: improve invalid frame detection code.
b852f84 Lib: Add missing amqp_get_server_properties() function.
7001e82 Lib: Add missing ssize_t on Win32 (emazv72)
c2ce2cb Lib: Correctly specify WINVER on Win32 when unspecified.
fe844e4 CMake: specify -DHAVE_CONFIG_H in examples.
932de5f Lib: correct time computation on Win32 (jestor)
3e83192 HPUX: use gethrtime on HP-UX for timers.
cb1b44e HPUX: correct include location of sys/uio.h
8ce585d Lib: incorrect OOM condition when 0-lenth exchange name is received.
c7716b8 CMake: correct htonll detection code on platforms defined with a macro.
4dc4eda Lib: remove unused assignment.
45302cf Lib: remove range-check of channel-ids.

(fhajny)