Fix long long little endian detection when cross-compiling

The long long endian detection code does an AC_TRY_RUN() and since that
doesn't work when cross-compiling, it sets a fallback value.  However,
rather than do any sort of default endian detection, the code simply
sets it to "no".  This probably breaks most little endian systems out
there when cross-compiling for them.  It certainly breaks Blackfin
systems.  So use the common endian detection code provided by autoconf
and key off of that when cross-compiling.

* configure.ac: Call AC_C_BIGENDIAN.
* m4/long_long.m4 (AC_LITTLE_ENDIAN_LONG_LONG): Set cross-compiling
logic based on ac_cv_c_bigendian.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/configure.ac b/configure.ac
index 483694c..e9df438 100644
--- a/configure.ac
+++ b/configure.ac
@@ -184,6 +184,7 @@
 AC_PROG_GCC_TRADITIONAL
 AC_PROG_INSTALL
 AC_C_CONST
+AC_C_BIGENDIAN
 AC_HEADER_STDC
 AC_HEADER_STDBOOL
 AC_HEADER_DIRENT
diff --git a/m4/long_long.m4 b/m4/long_long.m4
index 98ca370..5c5c80a 100644
--- a/m4/long_long.m4
+++ b/m4/long_long.m4
@@ -57,8 +57,12 @@
 		return 0;
 	return 1;
 }
-]])],[ac_cv_have_little_endian_long_long=yes],[ac_cv_have_little_endian_long_long=no],[# Should try to guess here
-ac_cv_have_little_endian_long_long=no
+]])],[ac_cv_have_little_endian_long_long=yes],[ac_cv_have_little_endian_long_long=no],[
+if test "x$ac_cv_c_bigendian" = "xyes"; then
+	ac_cv_have_little_endian_long_long=no
+else
+	ac_cv_have_little_endian_long_long=yes
+fi
 ])])
 AC_MSG_RESULT($ac_cv_have_little_endian_long_long)
 if test "$ac_cv_have_little_endian_long_long" = yes