AC_CHECK_LIB(seq, getpseudotty)
+dnl | add compiler warnings only if compiler understands them
+AC_MSG_CHECKING(whether compiler understands -Wall -Wno-parentheses)
+SAVE_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Wall -Wno-parentheses"
+AC_TRY_COMPILE([],[],
+ AC_MSG_RESULT(yes),
+ AC_MSG_RESULT(no)
+ CFLAGS="$SAVE_CFLAGS")
+
dnl | check for X-libraries
AC_PATH_XTRA