patch 9.0.1791: No tests for the termdebug plugin

Problem:  No tests for the termdebug plugin
Solution: Add some simple tests for the termdebug plugin

closes: #12927

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index fbdc3c7..e2e29f1 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -290,6 +290,7 @@
 	test_taglist \
 	test_tcl \
 	test_termcodes \
+	test_termdebug \
 	test_termencoding \
 	test_terminal \
 	test_terminal2 \
@@ -523,6 +524,7 @@
 	test_taglist.res \
 	test_tcl.res \
 	test_termcodes.res \
+	test_termdebug.res \
 	test_termencoding.res \
 	test_terminal.res \
 	test_terminal2.res \