patch 8.2.3019: location list only has the start position.

Problem:    Location list only has the start position.
Solution:   Make it possible to add an end position. (Shane-XB-Qian,
            closes #8393)

runtime/doc/eval.txt

@@ -5841,7 +5841,10 @@ getqflist([{what}])					*getqflist()*
 				bufname() to get the name
 			module	module name
 			lnum	line number in the buffer (first line is 1)
+			end_lnum
+				end of line number if the item is multiline
 			col	column number (first column is 1)
+			end_col	end of column number if the item has range
 			vcol	|TRUE|: "col" is visual column
 				|FALSE|: "col" is byte index
 			nr	error number