Merge pull request #2905 from Patsakas/Patsakas-fix-acl-bug

Fix NULL pointer increment in archive_acl_from_text_nl

(Not a security issue, and arguably not really even a bug, but easy to fix regardless.)

(cherry picked from commit 0b0b888f86)

libarchive/archive_acl.c

@@ -1755,7 +1755,6 @@ archive_acl_from_text_nl(struct archive_acl *acl, const char *text,
 
 			tag = 0;
 			s = field[n].start;
-			st = field[n].start + 1;
 			len = field[n].end - field[n].start;
 
 			if (len == 0) {
@@ -1763,6 +1762,8 @@ archive_acl_from_text_nl(struct archive_acl *acl, const char *text,
 				continue;
 			}
 
+			st = s + 1; 
+
 			switch (*s) {
 			case 'u':
 				if (len == 1 || (len == 4