patch 8.0.1012: MS-Windows: problem with $HOME when is was set internally

Problem:    MS-Windows: Problem with $HOME when is was set internally.
Solution:   Only use the $HOME default internally. (Yasuhiro Matsumoto, closes
            #2013)
diff --git a/src/Makefile b/src/Makefile
index e4da3b4..ecf14bc 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2278,6 +2278,7 @@
 	test_visual \
 	test_window_cmd \
 	test_window_id \
+	test_windows_home \
 	test_writefile \
 	test_alot_latin \
 	test_alot_utf8 \