Merge lp://qastaging/~msabramo/libmemcached/1190240 into lp://qastaging/libmemcached/1.0

Without this change, I get the following when trying to build pylibmc against libmemcached-1.0.17 installed in /home/vagrant/sw:

```
(py26.venv)vagrant@lucid64:~/dev/git-repos/pylibmc$ git log -n 1
commit c51e7525dfbc5152e034fd0332ccb04b05b63a42
Merge: b629523 eae786c
Author: Ludvig Ericson <email address hidden>
Date: Tue Jul 30 06:44:11 2013 -0700

    Merge pull request #123 from ketralnis/biggil

    Performance improvements to `inflate`
(py26.venv)vagrant@lucid64:~/dev/git-repos/pylibmc$ CFLAGS="-I/home/vagrant/sw/include" LDFLAGS="-L/home/vagrant/sw/lib" python setup.py build
running build
running build_py
running build_ext
building '_pylibmc' extension
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -I/home/vagrant/sw/include -fPIC -DUSE_ZLIB -I/usr/include/python2.6 -c src/_pylibmcmodule.c -o build/temp.linux-x86_64-2.6/src/_pylibmcmodule.o -fno-strict-aliasing
src/_pylibmcmodule.c:1848: error: expected declaration specifiers or '...' before 'memcached_server_instance_st'
src/_pylibmcmodule.c: In function '_PylibMC_AddServerCallback':
src/_pylibmcmodule.c:1896: error: 'instance' undeclared (first use in this function)
src/_pylibmcmodule.c:1896: error: (Each undeclared identifier is reported only once
src/_pylibmcmodule.c:1896: error: for each function it appears in.)
error: command 'gcc' failed with exit status 1
```

With this change applied and a new libmemcached installed in /home/vagrant/sw, pylibmc builds and the tests pass:

```
(py26.venv)vagrant@lucid64:~/dev/git-repos/pylibmc$ CFLAGS="-I/home/vagrant/sw/include" LDFLAGS="-L/home/vagrant/sw/lib" python setup.py build
running build
running build_py
running build_ext
building '_pylibmc' extension
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -I/home/vagrant/sw/include -fPIC -DUSE_ZLIB -I/usr/include/python2.6 -c src/_pylibmcmodule.c -o build/temp.linux-x86_64-2.6/src/_pylibmcmodule.o -fno-strict-aliasing
gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -L/home/vagrant/sw/lib -I/home/vagrant/sw/include build/temp.linux-x86_64-2.6/src/_pylibmcmodule.o -lmemcached -lz -o build/lib.linux-x86_64-2.6/_pylibmc.so

(py26.venv)vagrant@lucid64:~/dev/git-repos/pylibmc$ LD_LIBRARY_PATH=/home/vagrant/sw/lib python bin/runtests.py
nose.plugins.pylibmc: INFO: path to dev build: build/lib.linux-x86_64-2.6
nose.plugins.pylibmc: INFO: loaded _pylibmc from build/lib.linux-x86_64-2.6/_pylibmc.so
nose.plugins.pylibmc: INFO: testing pylibmc 1.3.100-dev for libmemcached 1.0.17 (compression=True, sasl=False)
...........................
----------------------------------------------------------------------
Ran 27 tests in 13.905s

OK
```