patch 8.2.0849: BeOS code is not maintained and probably unused

Problem:    BeOS code is not maintained and probably unused.
Solution:   Remove the BeOS code. (Emir Sari, closes #5817)
diff --git a/src/pty.c b/src/pty.c
index 03c02af..5f8b9e5 100644
--- a/src/pty.c
+++ b/src/pty.c
@@ -386,7 +386,7 @@
 static char PtyProto[] = "/dev/ptym/ptyXY";
 static char TtyProto[] = "/dev/pty/ttyXY";
 # else
-#  if defined (__BEOS__) || defined(__HAIKU__)
+#  ifdef(__HAIKU__)
 static char PtyProto[] = "/dev/pt/XY";
 static char TtyProto[] = "/dev/tt/XY";
 #  else