mod_auth_basic: Use unsigned bit flags (otherwise the non-zero value to be used is -1).

Merge r1603863 from trunk.
Submitted by: ylavic
Reviewed by: ylavic, jorton, rpluem
Github: closes #425


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1916584 13f79535-47bb-0310-9956-ffa450edef68

Author: ylavic

modules/aaa/mod_auth_basic.c

@@ -40,9 +40,9 @@ typedef struct {
     ap_expr_info_t *fakeuser;
     ap_expr_info_t *fakepass;
     const char *use_digest_algorithm;
-    int fake_set:1;
-    int use_digest_algorithm_set:1;
-    int authoritative_set:1;
+    unsigned int fake_set:1,
+                 use_digest_algorithm_set:1,
+                 authoritative_set:1;
 } auth_basic_config_rec;
 
 static void *create_auth_basic_dir_config(apr_pool_t *p, char *d)