Endianness is wrong if <endian.h> header is not available

TProtocol expects the header <endian.h> to be available, otherwise it relies on <boost/config.hpp>, but

• boost/config does not define endianness, that's done by <boost/detail/endian.hpp>
• even if it was, boost only defines the macro depending on the type (so either BOOST_LITTLE_ENDIAN or BOOST_BIG_ENDIAN) and does not, as in <endian.h> set a value.

As result, if <endian.h> is not available, the code always uses big endianness.

The simplest solution is to include the right header and define those values using the information boost provides.