AC_CHECK_HEADERS([arpa/inet.h ctype.h fcntl.h limits.h netdb.h netinet/in.h \
stdlib.h string.h sys/socket.h sys/time.h sys/timeb.h sys/un.h \
sys/ipc.h unistd.h utime.h stddef.h],
[], [AC_MSG_ERROR([$ac_header not found])])
AC_CHECK_HEADERS([arpa/inet.h ctype.h fcntl.h limits.h netdb.h netinet/in.h \
stdlib.h string.h sys/socket.h sys/time.h sys/timeb.h sys/un.h \
sys/ipc.h unistd.h utime.h stddef.h],
[], [AC_MSG_ERROR([$ac_header not found])])