Fixes #9110

git-svn-id: http://svn.boost.org/svn/boost/trunk@86165 b8fc166d-592f-0410-95f2-cb63ce0dd405
Address endian compile errors for OSX in the cases where sys/param.h was include ahead of the predef headers. The solution was to: use the OSX machine/endian.h header, and only allow a single OS to be detected at once. Test cases added for both conditions on OSX.

git-svn-id: http://svn.boost.org/svn/boost/trunk@86167 b8fc166d-592f-0410-95f2-cb63ce0dd405