patch 8.0.0462: failure of an MS-Windows test may go unnoticed

Problem:    If an MS-Windows tests succeeds at first and then fails in a way
            it does not produce a test.out file it looks like the test
            succeeded.
Solution:   Delete the previous output file.

src/testdir/Make_dos.mak

@@ -44,6 +44,7 @@ $(DOSTMP_INFILES): $(*B).in
 # This moves test99.in to test99.in.bak temporarily.
 $(TEST_OUTFILES): $(DOSTMP)\$(*B).in
 	-@if exist test.out DEL test.out
+	-@if exist $(DOSTMP)\$(*B).out DEL $(DOSTMP)\$(*B).out
 	move $(*B).in $(*B).in.bak > nul
 	copy $(DOSTMP)\$(*B).in $(*B).in > nul
 	copy $(*B).ok test.ok > nul

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    462,
 /**/
     461,
 /**/