patch 9.1.1476: no easy way to deduplicate text

Problem:  no easy way to deduplicate text
Solution: add the :uniq ex command
          (Hirohito Higashi)

closes: #17538

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/ex_getln.c b/src/ex_getln.c
index a956023..36775ba 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -276,7 +276,8 @@
 	else if (*cmd == 's' && cmd[1] == 'n')
 	    magic_overruled = OPTION_MAGIC_OFF;
     }
-    else if (STRNCMP(cmd, "sort", MAX(p - cmd, 3)) == 0)
+    else if (STRNCMP(cmd, "sort", MAX(p - cmd, 3)) == 0
+	    || STRNCMP(cmd, "uniq", MAX(p - cmd, 3)) == 0)
     {
 	// skip over ! and flags
 	if (*p == '!')