patch 8.1.2103: wrong error message if "termdebugger" is not executable

Problem:    wrong error message if "termdebugger" is not executable.
Solution:   Check if "termdebugger" is executable and give a clear error
            message. (Ozaki Kiichi, closes #5000)  Fix indents.
diff --git a/src/version.c b/src/version.c
index f5b9d60..fe9cee3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2103,
+/**/
     2102,
 /**/
     2101,