patch 9.1.0351: No test that completing a partial mapping clears 'showcmd'

Problem:  No test that completing a partial mapping clears 'showcmd'.
Solution: Complete partial mappings in Test_showcmd_part_map() instead
          of using :echo.  Adjust some comments (zeertzjq).

closes: #14580

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index 3754073..7eb6eab 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    351,
+/**/
     350,
 /**/
     349,