patch 8.2.0320: no Haiku support

Problem:    No Haiku support.
Solution:   Add support for Haiku. (Emir Sari, closes #5605)
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index a48e9ea..df8aba2 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -3769,7 +3769,7 @@
 		'guitablabel' can be used to change the text in the labels.
 		When 'e' is missing a non-GUI tab pages line may be used.
 		The GUI tabs are only supported on some systems, currently
-		GTK, Motif, Mac OS/X and MS-Windows.
+		GTK, Motif, Mac OS/X, Haiku, and MS-Windows.
 								*'go-f'*
 	  'f'	Foreground: Don't use fork() to detach the GUI from the shell
 		where it was started.  Use this for programs that wait for the
@@ -6207,6 +6207,11 @@
 					Macintosh: "$VIM:vimfiles,
 						$VIMRUNTIME,
 						$VIM:vimfiles:after"
+					Haiku: "$BE_USER_SETTINGS/vim,
+						$VIM/vimfiles,
+						$VIMRUNTIME,
+						$VIM/vimfiles/after,
+						$BE_USER_SETTINGS/vim/after")
 					VMS: "sys$login:vimfiles,
 						$VIM/vimfiles,
 						$VIMRUNTIME,
@@ -7665,6 +7670,7 @@
 				      in the GUI: "builtin_gui"
 					on Amiga: "amiga"
 					 on BeOS: "beos-ansi"
+					on Haiku: "xterm"
 					  on Mac: "mac-ansi"
 					 on MiNT: "vt52"
 					 on Unix: "ansi"