patch 9.1.0760: tests: no error reported, if gen_opt_test.vim fails

Problem:  tests: no error reported, if gen_opt_test.vim fails
Solution: Make Vim exit with return code 1 in case of any error
          (Milly)

closes: #15795

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/Make_mvc.mak b/src/testdir/Make_mvc.mak
index 1bf9eae..bb38e25 100644
--- a/src/testdir/Make_mvc.mak
+++ b/src/testdir/Make_mvc.mak
@@ -152,7 +152,7 @@
 	@del vimcmd
 
 opt_test.vim: ../optiondefs.h gen_opt_test.vim
-	$(VIMPROG) -u NONE -S gen_opt_test.vim --noplugin --not-a-term ../optiondefs.h
+	$(VIMPROG) -e -s -u NONE $(COMMON_ARGS) --nofork -S gen_opt_test.vim ../optiondefs.h
 
 test_bench_regexp.res: test_bench_regexp.vim
 	-if exist benchmark.out del benchmark.out