Implemented autoconf check for libtirpc

This library is needed to build testcases/network/rpc/rpc-tirpc.

Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
diff --git a/configure.ac b/configure.ac
index 9f397e7..97cb4da 100644
--- a/configure.ac
+++ b/configure.ac
@@ -178,5 +178,6 @@
 LTP_CHECK_MKNODAT
 LTP_CHECK_FALLOCATE
 LTP_CHECK_SYSCALL_FCNTL
+LTP_CHECK_TIRPC
 
 AC_OUTPUT