configure.ac: Add <pty.h> include for openpty

Another Clang 16ish fix (which makes -Wimplicit-function-declaration
an error by default).  github PR#355.

See: 2efd71da49b9cfeab7987058cf5919e473ff466b
See: be197635329feb839865fdc738e34e24afd1fca8

diff --git a/configure.ac b/configure.ac
index 1e77ecfc3e5549f6044a695c97ac607881bbd340..1866aea53dc4a0e243885468e911b8ef9975705a 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -2373,6 +2373,9 @@ if test ! -z "$check_for_openpty_ctty_bug"; then
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#ifdef HAVE_PTY_H
+# include <pty.h>
+#endif
 #include <sys/fcntl.h>
 #include <sys/types.h>
 #include <sys/wait.h>