patch 9.1.0854: cannot get terminal cell size

Problem:  cannot get terminal cell size
Solution: add getcellpixels() function to return xpixel * ypixel
          cell size on terminal Unix (mikoto2000)

closes: #16004

Signed-off-by: mikoto2000 <mikoto2000@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/usr_41.txt b/runtime/doc/usr_41.txt
index af67429..36907d2 100644
--- a/runtime/doc/usr_41.txt
+++ b/runtime/doc/usr_41.txt
@@ -1,4 +1,4 @@
-*usr_41.txt*	For Vim version 9.1.  Last change: 2024 Oct 05
+*usr_41.txt*	For Vim version 9.1.  Last change: 2024 Nov 11
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -778,6 +778,7 @@
 	strdisplaywidth()	size of string when displayed, deals with tabs
 	setcellwidths()		set character cell width overrides
 	getcellwidths()		get character cell width overrides
+	getcellpixels()		get character cell pixel size
 	reverse()		reverse the order of characters in a string
 	substitute()		substitute a pattern match with a string
 	submatch()		get a specific match in ":s" and substitute()
@@ -1394,6 +1395,7 @@
 	did_filetype()		check if a FileType autocommand was used
 	diff()			diff two Lists of strings
 	eventhandler()		check if invoked by an event handler
+	getcellpixels()		get List of cell pixel size
 	getpid()		get process ID of Vim
 	getscriptinfo()		get list of sourced vim scripts
 	getimstatus()		check if IME status is active