t3700: Skip a test with backslashes in pathspec

The test verifies that glob special characters can be escaped with
backslashes.  In particular, the string fo\[ou\]bar is given to git.

On Windows, this does not work because backslashes are first of all
directory separators, and first thing git does with a pathspec from the
command line is to convert backslashes to forward slashes.
Signed-off-by: NJohannes Sixt <j6t@kdbg.org>

t/t3700-add.sh

@@ -222,7 +222,7 @@ test_expect_success POSIXPERM 'git add (add.ignore-errors = false)' '
 	! ( git ls-files foo1 | grep foo1 )
 '
 
-test_expect_success 'git add '\''fo\[ou\]bar'\'' ignores foobar' '
+test_expect_success BSLASHPSPEC "git add 'fo\\[ou\\]bar' ignores foobar" '
 	git reset --hard &&
 	touch fo\[ou\]bar foobar &&
 	git add '\''fo\[ou\]bar'\'' &&

t/test-lib.sh

@@ -688,9 +688,11 @@ case $(uname -s) in
 		builtin pwd -W
 	}
 	# no POSIX permissions
+	# backslashes in pathspec are converted to '/'
 	;;
 *)
 	test_set_prereq POSIXPERM
+	test_set_prereq BSLASHPSPEC
 	;;
 esac