lapi: Add configure check and fallback struct iovec declaration

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
diff --git a/configure.ac b/configure.ac
index 00e4322..161b198 100644
--- a/configure.ac
+++ b/configure.ac
@@ -189,5 +189,6 @@
 LTP_CHECK_VMSPLICE
 LTP_CHECK_TIMERFD
 LTP_CHECK_CAN_SUPPORT
+LTP_CHECK_IOVEC
 
 AC_OUTPUT