* configure.ac (--with-file-notification): Add kqueue.
(top): Remove special test for "${HAVE_NS}" and
${with_file_notification}, this is handled inside gfilenotify
tests. Add kqueue tests. Use NOTIFY_CFLAGS and NOTIFY_LIBS
instead of library specific variables.
* src/Makefile.in: Use NOTIFY_CFLAGS and NOTIFY_LIBS.
* src/emacs.c (main): Call globals_of_kqueue and syms_of_kqueue.
* src/kqueue.c: New file.
* src/lisp.h: Declare extern globals_of_kqueue and syms_of_kqueue.