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: Kevin Ballard <kevin@sb.org>
Signed-off-by: Junio 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 == '\\';
 }
 
 /*