- clang defines unix, __unix and __unix__, base gcc only defines __unix__
- stop assuming that non-x86 archs are all little-endian

Index: willuslib/willus.h
--- willuslib/willus.h.orig
+++ willuslib/willus.h
@@ -107,7 +107,7 @@ typedef double  real;
 #define MINGW
 #endif
 
-#if (!defined(UNIX) && (defined(DJEMX) || defined(MINGW) || defined(CYGWIN32) || defined(unix) || defined(__unix) || defined(__MACH__)))
+#if (!defined(UNIX) && (defined(DJEMX) || defined(MINGW) || defined(CYGWIN32) || defined(unix) || defined(__unix) || defined(__unix__) || defined(__MACH__)))
 #define UNIX
 #endif
 
@@ -160,7 +160,8 @@ typedef double  real;
 #define WILLUS_X86
 #endif
 
-#if (!defined(WILLUS_BIGENDIAN) && !defined(WILLUS_X86))
+#include <endian.h>
+#if (!defined(WILLUS_BIGENDIAN) && BYTE_ORDER == BIG_ENDIAN)
 #define WILLUS_BIGENDIAN
 #endif