GitLab

Roll Protobuf r415:r423.                                                                                                                                                                                                                                                         

1) Got an upstream diff 415:423 from svn
2) Applied
3) Updated protobuf.gyp

Changelog:

r423 Add support for NaCl in atomicops.
r422 Fix issue/333. skip any escaped characters in quotes.
r421 -lz in protobuf.pc belongs in Libs.private, not Libs 
r420 set _VARDADIC_MAX=10 preprocessor definition to make test pass in vc11.
r419 Allow configure to disable maintainer mode 
r418 Update atomicops to support new platforms where intptr_t = long.
r417 Fix a NULL/bool conversion.
r416 Fix issue 378

Review URL: https://chromiumcodereview.appspot.com/10793026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148557 0039d316-1c4b-4281-b951-d872f2087c98