Richard W.M. Jones wrote:
...
-AC_CHECK_HEADERS([errno.h sys/types.h sys/un.h sys/wait.h
sys/socket.h])
+AC_CHECK_HEADERS([errno.h sys/types.h sys/un.h sys/wait.h sys/socket.h netinet/in.h
arpa/inet.h])
dnl Check for rpcgen and XDR library. rpcgen is optional.
AC_CHECK_PROG([RPCGEN],[rpcgen],[rpcgen],[no])
you probably want to use gnulib's netinet_in module instead.
Then you can #include <netinet/in.h> unconditionally.