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_ming.mak b/src/testdir/Make_ming.mak
index 2676111..f26950e 100644
--- a/src/testdir/Make_ming.mak
+++ b/src/testdir/Make_ming.mak
@@ -158,7 +158,7 @@
 	@$(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
 	-$(DEL) benchmark.out