In preparation for updating Boost to 1.60, add include guards from more Boost
headers to the list of macros that moc automatically defines when processing
files. As explained in r408911, Qt4's moc cannot parse some constructs used by
a few Boost headers, so we define their include guards to make moc skip them.
This is a cleaner approach that allows us to largely revert r408472, r408473,
r408474, r408475, r408502, r408773 and r408419, which added several patches to
many ports to work around this moc bug.
PR: 199601
PR: 208322
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