Trap SIGBUS when Configure checks for va_copy (#18148)

On several systems the attempt to determine if we "need va_copy() or
similar" results in a SIGBUS instead of a SIGSEGV because the fault
happens pointing at an io device address.

While reviewing accounting logs during the OpenBSD system build, bluhm@
noticed a core dump and deraadt@ tracked it down.

While researching it was discovered that this is a fairly common case in
other systems as well.

Original diff by deraadt@

(cherry picked from commit bec07c3af574f0f22a318c6273a2c4f29afc1251)

1 files changed, 3 insertions, 0 deletions

diff --git a/Configure b/Configure
index cef8c3c078..fbc225822a 100755
--- a/Configure
+++ b/Configure
@@ -21477,6 +21477,9 @@ int
 main(int ac, char **av)
 {
   signal(SIGSEGV, exit);
+#ifdef SIGBUS
+  signal(SIGBUS,  exit);
+#endif
 
   myprintf("%s%cs all right, then\n", "that", '\'');
   exit(0);