patch 8.0.1336: cannot use imactivatefunc() unless compiled with +xim

Problem:    Cannot use imactivatefunc() unless compiled with +xim.
Solution:   Allow using imactivatefunc() when not compiled with +xim.
            (Yasuhiro Matsumoto, closes #2349)
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index f9acff8..d71e7f9 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -4256,8 +4256,7 @@
 'imactivatefunc' 'imaf'	string (default "")
 			global
 			{not in Vi}
-			{only available when compiled with |+xim| and
-			|+GUI_GTK|}
+			{only available when compiled with |+mbyte|}
 	This option specifies a function that will be called to
 	activate/inactivate Input Method.
 
@@ -4308,8 +4307,7 @@
 'imcmdline' 'imc'	boolean (default off)
 			global
 			{not in Vi}
-			{only available when compiled with the |+xim|,
-			|+multi_byte_ime| or |global-ime| features}
+			{only available when compiled with |+mbyte|}
 	When set the Input Method is always on when starting to edit a command
 	line, unless entering a search pattern (see 'imsearch' for that).
 	Setting this option is useful when your input method allows entering
@@ -4320,8 +4318,7 @@
 'imdisable' 'imd'	boolean (default off, on for some systems (SGI))
 			global
 			{not in Vi}
-			{only available when compiled with the |+xim|,
-			|+multi_byte_ime| or |global-ime| features}
+			{only available when compiled with |+mbyte|}
 	When set the Input Method is never used.  This is useful to disable
 	the IM when it doesn't work properly.
 	Currently this option is on by default for SGI/IRIX machines.  This
@@ -4336,8 +4333,6 @@
 		0	:lmap is off and IM is off
 		1	:lmap is ON and IM is off
 		2	:lmap is off and IM is ON
-	2 is available only when compiled with the |+multi_byte_ime|, |+xim|
-	or |global-ime|.
 	To always reset the option to zero when leaving Insert mode with <Esc>
 	this can be used: >
 		:inoremap <ESC> <ESC>:set iminsert=0<CR>
@@ -4350,6 +4345,10 @@
 	The value 0 may not work correctly with Athena and Motif with some XIM
 	methods.  Use 'imdisable' to disable XIM then.
 
+	You can set 'imactivatefunc' and 'imstatusfunc' to handle IME/XIM
+	via external command if vim is not compiled with the |+xim|,
+	|+multi_byte_ime| or |global-ime|.
+
 						*'imsearch'* *'ims'*
 'imsearch' 'ims'	number (default -1)
 			local to buffer
@@ -4372,8 +4371,7 @@
 'imstatusfunc' 'imsf'	string (default "")
 			global
 			{not in Vi}
-			{only available when compiled with |+xim| and
-			|+GUI_GTK|}
+			{only available when compiled with |+mbyte|}
 	This option specifies a function that is called to obtain the status
 	of Input Method.  It must return a positive number when IME is active.