Check for endianness the POSIX way.

Index: nall/intrinsics.hpp
--- nall/intrinsics.hpp.orig
+++ nall/intrinsics.hpp
@@ -106,10 +106,8 @@ namespace nall {
 
 #if defined(PLATFORM_MACOS)
   #include <machine/endian.h>
-#elif defined(PLATFORM_LINUX)
+#elif defined(PLATFORM_LINUX) || defined(PLATFORM_BSD)
   #include <endian.h>
-#elif defined(PLATFORM_BSD)
-  #include <sys/endian.h>
 #endif
 
 /* Processor Detection */
@@ -143,10 +141,10 @@ namespace nall {
 
 namespace nall {
 
-#if (defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && __BYTE_ORDER == __LITTLE_ENDIAN) || defined(__LITTLE_ENDIAN__) || defined(__i386__) || defined(__amd64__) || defined(_M_IX86) || defined(_M_AMD64)
+#if (defined(BYTE_ORDER) && BYTE_ORDER == LITTLE_ENDIAN) || (defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && __BYTE_ORDER == __LITTLE_ENDIAN) || defined(__LITTLE_ENDIAN__) || defined(__i386__) || defined(__amd64__) || defined(_M_IX86) || defined(_M_AMD64)
   #define ENDIAN_LSB
   auto Intrinsics::endian() -> Endian { return Endian::LSB; }
-#elif (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && __BYTE_ORDER == __BIG_ENDIAN) || defined(__BIG_ENDIAN__) || defined(__powerpc__) || defined(_M_PPC)
+#elif (defined(BYTE_ORDER) && BYTE_ORDER == BIG_ENDIAN) || (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && __BYTE_ORDER == __BIG_ENDIAN) || defined(__BIG_ENDIAN__) || defined(__powerpc__) || defined(_M_PPC)
   #define ENDIAN_MSB
   auto Intrinsics::endian() -> Endian { return Endian::MSB; }
 #else