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/src/search.c b/src/search.c
index 5222a43..ea7e654 100644
--- a/src/search.c
+++ b/src/search.c
@@ -439,7 +439,7 @@
 }
 
 /*
- * As ignorecase() put pass the "ic" and "scs" flags.
+ * As ignorecase() but pass the "ic" and "scs" flags.
  */
     int
 ignorecase_opt(char_u *pat, int ic_in, int scs)