Fix escaping of glob special characters in pathspecs

match_one implements an optimized pathspec match where it only uses
fnmatch if it detects glob special characters in the pattern. Unfortunately
it didn't treat \ as a special character, so attempts to escape a glob
special character would fail even though fnmatch() supports it.
Signed-off-by: NKevin Ballard <kevin@sb.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

dir.c

@@ -54,7 +54,7 @@ int common_prefix(const char **pathspec)
 
 static inline int special_char(unsigned char c1)
 {
-	return !c1 || c1 == '*' || c1 == '[' || c1 == '?';
+	return !c1 || c1 == '*' || c1 == '[' || c1 == '?' || c1 == '\\';
 }
 
 /*

t/t3700-add.sh

@@ -222,4 +222,12 @@ test_expect_success 'git add (add.ignore-errors = false)' '
 	! ( git ls-files foo1 | grep foo1 )
 '
 
+test_expect_success 'git add '\''fo\?bar'\'' ignores foobar' '
+	git reset --hard &&
+	touch fo\?bar foobar &&
+	git add '\''fo\?bar'\'' &&
+	git ls-files fo\?bar | grep -F fo\?bar &&
+	! ( git ls-files foobar | grep foobar )
+'
+
 test_done