Replaces local endianity testing macro with the common one.

That makes it easier to integrate BIRD to crosscompiling
buildsystems.

aclocal.m4

@@ -26,6 +26,7 @@ for size in 1 2 4 ; do
 	done
 ])
 
+dnl BIRD_CHECK_ENDIAN is unused and obsolete
 AC_DEFUN(BIRD_CHECK_ENDIAN,
 [AC_CACHE_CHECK([CPU endianity], bird_cv_c_endian,[
 AC_TRY_RUN([

configure.in

@@ -179,8 +179,10 @@ AC_TRY_COMPILE([#include <sys/types.h>
   AC_DEFINE(HAVE_SIN_LEN,,sin_len)],
   AC_MSG_RESULT(no))
 
+AC_C_BIGENDIAN([AC_DEFINE(CPU_BIG_ENDIAN)], [AC_DEFINE(CPU_LITTLE_ENDIAN)],
+		 [AC_MSG_ERROR([Cannot determine CPU endianity.])])
+
 BIRD_CHECK_INTEGERS
-BIRD_CHECK_ENDIAN
 BIRD_CHECK_STRUCT_ALIGN
 BIRD_CHECK_TIME_T
 BIRD_CHECK_STRUCT_IP_MREQN