Fix wrong type for syscall.Setrlimit on FreeBSD (#244)

Values are uint64 on Unix but FreeBSD uses int64 for legacy reasons.

src/app/spreed-webrtc-server/main.go

@@ -367,13 +367,13 @@ func runner(runtime phoenix.Runtime) error {
 	// Try to increase number of file open files. This only works as root.
 	maxfd, err := runtime.GetInt("http", "maxfd")
 	if err == nil {
-		rLimit.Max = uint64(maxfd)
-		rLimit.Cur = uint64(maxfd)
+		rLimit.Max = rlimitType(maxfd)
+		rLimit.Cur = rlimitType(maxfd)
 		err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
 		if err != nil {
 			log.Println("Error setting max open files", err)
 		} else {
-			log.Printf("Set max open files successfully to %d\n", uint64(maxfd))
+			log.Printf("Set max open files successfully to %d\n", rlimitType(maxfd))
 		}
 	}
 

src/app/spreed-webrtc-server/types_freebsd.go

@@ -0,0 +1,11 @@
+// +build freebsd
+
+package main
+
+// Rlimit values are int64 in FreeBSD.
+// https://golang.org/src/syscall/ztypes_freebsd_amd64.go
+// Intentionally signed, because of legacy code that uses -1 for
+// RLIM_INFINITY.
+func rlimitType(value int) int64 {
+	return int64(value)
+}

src/app/spreed-webrtc-server/types_unix.go

@@ -0,0 +1,8 @@
+// +build !freebsd
+
+package main
+
+// On Unix, rLimit values are uint64.
+func rlimitType(value int) uint64 {
+	return uint64(value)
+}