patch 8.0.0456: typo in MinGW test makefile

Problem:    Typo in MinGW test makefile.
Solution:   Change an underscore to a dot. (Michael Soyka)

Author: brammool

src/testdir/Make_ming.mak

@@ -129,7 +129,7 @@ test_gui.res: test_gui.vim
 
 test_gui_init.res: test_gui_init.vim
 	@echo "$(VIMPROG)" > vimcmd
-	$(VIMPROG) -u gui_preinit_vim -U gui_init.vim $(NO_PLUGINS) -S runtest.vim $<
+	$(VIMPROG) -u gui_preinit.vim -U gui_init.vim $(NO_PLUGINS) -S runtest.vim $<
 	@$(DEL) vimcmd
 
 opt_test.vim: ../option.c gen_opt_test.vim

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    456,
 /**/
     455,
 /**/