AC_CHECK_FUNC([readdir], [], [AC_MSG_ERROR([readdir() unavailable])])
AC_CHECK_FUNC([ppoll], [], [AC_MSG_ERROR([ppoll() unavailable])])
AC_CHECK_HEADERS([getopt.h], [], [AC_MSG_ERROR([getopt.h header not found])])
-AC_CHECK_HEADERS([stdint.h], [], [AC_MSG_ERROR([stdint.h header not found])])
AC_CHECK_HEADERS([dirent.h], [], [AC_MSG_ERROR([dirent.h header not found])])
AC_CHECK_HEADERS([sys/poll.h], [], [AC_MSG_ERROR([sys/poll.h header not found])])
AC_CHECK_HEADERS([linux/gpio.h], [], [AC_MSG_ERROR([linux/gpio.h header not found])])