Autoindex: improved ngx_de_info() error handling.

This allows to build a directory listing whenever a loop exists in symbolic
link resolution of the path argument.

src/http/modules/ngx_http_autoindex_module.c

diff --git a/src/http/modules/ngx_http_autoindex_module.c b/src/http/modules/ngx_http_autoindex_module.c
index e21d8d7..2214551 100644
--- a/src/http/modules/ngx_http_autoindex_module.c
+++ b/src/http/modules/ngx_http_autoindex_module.c
@@ -304,7 +304,7 @@
             if (ngx_de_info(filename, &dir) == NGX_FILE_ERROR) {
                 err = ngx_errno;
 
-                if (err != NGX_ENOENT) {
+                if (err != NGX_ENOENT && err != NGX_ELOOP) {
                     ngx_log_error(NGX_LOG_CRIT, r->connection->log, err,
                                   ngx_de_info_n " \"%s\" failed", filename);
 

src/os/unix/ngx_errno.h

diff --git a/src/os/unix/ngx_errno.h b/src/os/unix/ngx_errno.h
index 125087e..1497c5f 100644
--- a/src/os/unix/ngx_errno.h
+++ b/src/os/unix/ngx_errno.h
@@ -49,10 +49,10 @@
 #define NGX_ECANCELED     ECANCELED
 #define NGX_EILSEQ        EILSEQ
 #define NGX_ENOMOREFILES  0
+#define NGX_ELOOP         ELOOP
 
 #if (NGX_HAVE_OPENAT)
 #define NGX_EMLINK        EMLINK
-#define NGX_ELOOP         ELOOP
 #endif
 
 #if (__hpux__)

src/os/win32/ngx_errno.h

diff --git a/src/os/win32/ngx_errno.h b/src/os/win32/ngx_errno.h
index 090ba1b..decb6fe 100644
--- a/src/os/win32/ngx_errno.h
+++ b/src/os/win32/ngx_errno.h
@@ -51,6 +51,7 @@
 #define NGX_EHOSTUNREACH           WSAEHOSTUNREACH
 #define NGX_ENOMOREFILES           ERROR_NO_MORE_FILES
 #define NGX_EILSEQ                 ERROR_NO_UNICODE_TRANSLATION
+#define NGX_ELOOP                  0
 
 #define NGX_EALREADY               WSAEALREADY
 #define NGX_EINVAL                 WSAEINVAL