patch 9.1.1374: completion: 'smartcase' not respected when filtering matches

Problem:  Currently, 'smartcase' is respected when completing keywords
          using <C-N>, <C-P>, <C-X><C-N>, and <C-X><C-P>. However, when
          a user continues typing and the completion menu is filtered
          using cached matches, 'smartcase' is not applied. This leads
          to poor-quality or irrelevant completion suggestions, as shown
          in the example below.
Solution: When filtering cached completion items after typing additional
          characters, apply case-sensitive comparison if 'smartcase' is
          enabled and the typed pattern includes uppercase characters.
          This ensures consistent and expected completion behavior.
          (Girish Palya)

closes: #17271

Signed-off-by: Girish Palya <girishji@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/version9.txt b/runtime/doc/version9.txt
index afa800d..371e4b3 100644
--- a/runtime/doc/version9.txt
+++ b/runtime/doc/version9.txt
@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2025 May 07
+*version9.txt*  For Vim version 9.1.  Last change: 2025 May 08
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41626,6 +41626,7 @@
   "{flag}^<limit>" notation
 - add ":filetype" command completion
 - add "filetypecmd" completion type for |getcompletion()|
+- 'smartcase' applies to completion filtering
 
 Options: ~
 - the default for 'commentstring' contains whitespace padding to have