Msgpack serialize/unserialize support for APCu

[ibobo]

Hi, I added support to use Msgpack as a serializer for APCu. This was needed to me because IgBinary is very unstable under PHP 7 (gives a Segmentation Fault whenever you try to use it as a session or APCu serializer) and I want to switch to the newer runtime version.

In the coming days I will do some more testing. If some of you have any suggestion on how to improve the pull request, I will be happy to fix it.

PS. I see the CI build fails for test 029 since it doesn't have APCu installed. Maybe I could add support for APC as well and update .travis.yml to use it. Let me know!

Thanks!

[codecov-io]

Codecov Report

Merging #93 into master will decrease coverage by -0.25%.

@@ Coverage Diff @@## master #93 +/- ## ========================================== - Coverage 87.19% 86.95% -0.25%  ========================================== Files 8 8 Lines 1234 1234 ========================================== - Hits 1076 1073 -3 - Misses 158 161 +3

Impacted Files	Coverage Δ
msgpack.c	92% <ø> (ø)	✅
msgpack_unpack.c	85.49% <ø> (-0.91%)	❌

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[andypost]

TEST 30/123 [tests/029.phpt] ========DIFF======== 005- APCu Serializer Support => enabled ========DONE======== FAIL Msgpack module info [tests/029.phpt] 

It looks like apu is not loaded when tests run

[andypost]

Other failed tests are not compatible with PHP 7 #109

[m6w6]

Hi! Thanks for this submission.

Please rebase this PR, so we can have a closer look!

[andypost]

#162 still looking for reviews