Ensure that <utmp.h> is only included when present and available.

--- openssh-9.4p1/configure.ac.old	2023-08-09 20:10:22.000000000 -0500
+++ openssh-9.4p1/configure.ac	2024-12-07 23:51:42.425820273 -0600
@@ -5351,7 +5351,9 @@
 AC_MSG_CHECKING([if your system defines LASTLOG_FILE])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <sys/types.h>
-#include <utmp.h>
+#ifdef HAVE_UTMP_H
+#  include <utmp.h>
+#endif
 #ifdef HAVE_LASTLOG_H
 #  include <lastlog.h>
 #endif
@@ -5368,7 +5370,9 @@
 		AC_MSG_CHECKING([if your system defines _PATH_LASTLOG])
 		AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <sys/types.h>
-#include <utmp.h>
+#ifdef HAVE_UTMP_H
+#  include <utmp.h>
+#endif
 #ifdef HAVE_LASTLOG_H
 #  include <lastlog.h>
 #endif
@@ -5406,7 +5410,9 @@
 AC_MSG_CHECKING([if your system defines UTMP_FILE])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <sys/types.h>
-#include <utmp.h>
+#ifdef HAVE_UTMP_H
+#  include <utmp.h>
+#endif
 #ifdef HAVE_PATHS_H
 #  include <paths.h>
 #endif
@@ -5436,7 +5442,9 @@
 AC_MSG_CHECKING([if your system defines WTMP_FILE])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <sys/types.h>
-#include <utmp.h>
+#ifdef HAVE_UTMP_H
+#  include <utmp.h>
+#endif
 #ifdef HAVE_PATHS_H
 #  include <paths.h>
 #endif
@@ -5466,7 +5474,9 @@
 AC_MSG_CHECKING([if your system defines WTMPX_FILE])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <sys/types.h>
-#include <utmp.h>
+#ifdef HAVE_UTMP_H
+#  include <utmp.h>
+#endif
 #ifdef HAVE_UTMPX_H
 #include <utmpx.h>
 #endif