Fix t1410 for core.filemode==false

Since c869753e, core.filemode is hardwired to false on Cygwin.
So this test had no chance to succeed, since an early commit
(changing just the filemode) failed, and therefore all subsequent
tests.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

t/t1410-reflog.sh

@@ -71,6 +71,8 @@ test_expect_success setup '
 	check_fsck &&
 
 	chmod +x C &&
+	( test "`git repo-config --bool core.filemode`" != false ||
+	  echo executable >>C ) &&
 	git add C &&
 	test_tick && git commit -m dragon &&
 	L=`git rev-parse --verify HEAD` &&