Add missing kqueue event filters on FreeBSD

CHANGELOG.md

@@ -50,6 +50,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#741](https://github.com/nix-rust/nix/pull/741))
 - Added more standard trait implementations for various types.
   ([#814](https://github.com/nix-rust/nix/pull/814))
+- Added `EVFILT_EMPTY`, `EVFILT_PROCDESC` and `EVFILT_SENDFILE` on FreeBSD.
+  ([#825](https://github.com/nix-rust/nix/pull/825))
 
 ### Changed
 - Use native `pipe2` on all BSD targets.  Users should notice no difference.

src/sys/event.rs

@@ -39,6 +39,9 @@ libc_enum! {
     #[cfg_attr(not(target_os = "netbsd"), repr(i16))]
     pub enum EventFilter {
         EVFILT_AIO,
+        /// Returns whenever there is no remaining data in the write buffer
+        #[cfg(target_os = "freebsd")]
+        EVFILT_EMPTY,
         #[cfg(target_os = "dragonfly")]
         EVFILT_EXCEPT,
         #[cfg(any(target_os = "dragonfly",
@@ -51,7 +54,15 @@ libc_enum! {
         #[cfg(any(target_os = "ios", target_os = "macos"))]
         EVFILT_MACHPORT,
         EVFILT_PROC,
+        /// Returns events associated with the process referenced by a given
+        /// process descriptor, created by pdfork(2). The events to monitor are:
+        /// 
+        /// - NOTE_EXIT: the process has exited. The exit status will be stored in data.
+        #[cfg(target_os = "freebsd")]
+        EVFILT_PROCDESC,
         EVFILT_READ,
+        #[cfg(target_os = "freebsd")]
+        EVFILT_SENDFILE,
         EVFILT_SIGNAL,
         EVFILT_TIMER,
         #[cfg(any(target_os = "dragonfly",