macosx defined a __APPLE__ not a MACOSX as previously found.
endian.h doesn't exists in mingw, and we emulate the necessary value (i.e. BYTE_ORDER and LITTLE_ENDIAN) directly in a #ifdef __MINGW32__. note that in mingw32 we hardcode the endianness to little endian. Contributed-by: Henk-Jan van Tuyl
… a common header.
…o avoid beeing flag as depending on hunit in the library.