sys/types: include endian.h, and fix endian definitions.

* Defining LITTLE/BIG_ENDIAN as 0 breaks some feature test macros,
  particularly in autoconf. Checking with FreeBSD, their macros
  define a non-zero value as well.

References:
- https://github.com/freebsd/freebsd/blob/master/sys/x86/include/endian.h
- http://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/c.m4#n1584
Change-Id: I61b0bbad74e2bf5248464a5c15e504b9f45bea7f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1526
Reviewed-by: Adrien Destugues <[email protected]>

headers/posix/endian.h

@@ -16,11 +16,11 @@
 
 #if defined(__HAIKU_LITTLE_ENDIAN)
 #	define LITTLE_ENDIAN	1234
-#	define BIG_ENDIAN		0
+#	define BIG_ENDIAN		4321
 #	define BYTE_ORDER		LITTLE_ENDIAN
 #elif defined(__HAIKU_BIG_ENDIAN)
 #	define BIG_ENDIAN		4321
-#	define LITTLE_ENDIAN	0
+#	define LITTLE_ENDIAN	1234
 #	define BYTE_ORDER		BIG_ENDIAN
 #endif
 
@@ -28,4 +28,4 @@
 #define __LITTLE_ENDIAN		LITTLE_ENDIAN
 #define __BYTE_ORDER		BYTE_ORDER
 
-#endif	/* _ENDIAN_H_ */
+#endif	/* _ENDIAN_H_ */

headers/posix/sys/types.h

@@ -122,6 +122,7 @@ struct _pthread_spinlock {
 };
 
 
+#include <endian.h>
 #include <null.h>
 #include <size_t.h>
 #include <time.h>