Configure tests for sigignore, but it's used
unconditionally.

--- libtest/main.cc.orig	Sun Nov  8 22:05:06 2015
+++ libtest/main.cc	Sun Nov  8 22:05:53 2015
@@ -288,7 +288,9 @@ int main(int argc, char *argv[])
     do
     {
       exit_code= EXIT_SUCCESS;
+#if defined(HAVE_SIGIGNORE)
       fatal_assert(sigignore(SIGPIPE) == 0);
+#endif
 
       libtest::SignalThread signal;
       if (signal.setup() == false)