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/testdir/Make_all.mak b/src/testdir/Make_all.mak
index ef86a7d..1cbede6 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -331,6 +331,7 @@
 	test_trycatch \
 	test_tuple \
 	test_undo \
+	test_uniq \
 	test_unlet \
 	test_user_func \
 	test_usercommands \
@@ -586,6 +587,7 @@
 	test_trycatch.res \
 	test_tuple.res \
 	test_undo.res \
+	test_uniq.res \
 	test_user_func.res \
 	test_usercommands.res \
 	test_vartabs.res \