Configure: add a test for SG_IO

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

configure.ac

@@ -91,6 +91,16 @@ if test x"$libiscsi_cv_HAVE_SOCKADDR_IN6" = x"yes"; then
     AC_DEFINE(HAVE_SOCKADDR_IN6,1,[Whether we have IPv6 support])
 fi
 
+AC_CACHE_CHECK([for SG_IO support],libiscsi_cv_HAVE_SG_IO,[
+AC_TRY_COMPILE([
+#include <unistd.h>
+#include <scsi/sg.h>],
+[int sgio = SG_IO;],
+libiscsi_cv_HAVE_SG_IO=yes,libiscsi_cv_HAVE_SG_IO=no)])
+if test x"$libiscsi_cv_HAVE_SG_IO" = x"yes"; then
+    AC_DEFINE(HAVE_SG_IO,1,[Whether we have SG_IO support])
+fi
+
 AC_MSG_CHECKING(whether libcunit is available)
 ac_save_CFLAGS="$CFLAGS"
 ac_save_LIBS="$LIBS"