...as the source files themselves include standard headers, which must not be
included from within a namespace (which confuses clang-cl).  According to Tor,
the original intent was to try not to pollute the global namespace, but that
seems to cause no problems in practice (esp. as nothing from these files gets
exported).

Change-Id: I204c1db932996a09d16e84dd5c6033caa5362caa